Hi BigRest,
Welcome … and I’m glad you found us. Thanks for the kind comments as well 
While I can certainly help with “how” to choose … It’s not possible to make specific suggestions or recommendations for either a mattress, manufacturers/retailers, or combinations of materials or components because the first “rule” of mattress shopping is to always remember that you are the only one that can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved that are unique to each person to use a formula or for anyone to be able to predict or make a specific suggestion or recommendation about which mattress or combination of materials and components or which type of mattress would be the best “match” for you in terms of “comfort”, firmness, or PPP (Posture and alignment, Pressure relief, and your own Personal preferences) or how a mattress will “feel” to you or compare to another mattress based on specs (either yours or a mattress), sleeping positions, health conditions, or “theory at a distance” that can possibly be more reliable than your own careful testing (hopefully using the testing guidelines in step 4 of the tutorial) or your own personal sleeping experience (see mattress firmness/comfort levels in post #2 here).
I’m assuming that you’ve read the mattress shopping tutorial here but two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort”, firmness, and PPP that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists based on all the parts of your personal value equation that are most important to you (including the price of course and the options you have available after a purchase if your choice doesn’t turn out as well as you hoped for).
While again nobody can speak to how any specific mattress will “feel” for someone else or whether it will be a good “match” in terms of comfort, firmness, and PPP because this is too subjective and relative to different body types, sleeping positions, and individual preferences, sensitivities, and circumstances and you are the only one that can feel what you feel on a mattress … outside of PPP (which is the most important part of “value”), the next most important part of the value of a mattress purchase is durability which is all about how long you will sleep well on a mattress. This is the part of your research that you can’t see or “feel” and assessing the durability and useful life of a mattress depends on knowing the specifics of its construction and the type and quality of the materials inside it regardless of the name of the manufacturer on the label or how a mattress feels in a showroom or when it is relatively new so I would always make sure that you find out information listed here so you can compare the quality of the materials and components to the durability guidelines here to make sure there are no lower quality materials or weak links in a mattress that would be a cause for concern relative to the durability and useful life of a mattress before making any purchase.
When you can’t test a mattress in person then the most reliable source of guidance is always a more detailed phone conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests at heart and who can help “talk you through” the specifics of their mattresses and the properties and “feel” of the materials they are using (fast or slow response, resilience, firmness etc) and the options they have available that may be the best “match” for you based on the information you provide them, any local testing you have done or mattresses you have slept on and liked or other mattresses you are considering that they are familiar with, and the “averages” of other customers that are similar to you. They will know more about “matching” their specific mattress designs and firmness levels to different body types, sleeping positions, and preferences (or to other mattresses that they are familiar with) than anyone else.
While knowing the specs that can affect the quality and durability of the layers and components in a mattress is always important … unless you have a great deal of knowledge and experience with different types of mattress materials and components and their specs and different layering combinations and mattress designs and how they combine together and can translate them into your own “real life” experience that can be unique to you (which would generally be a very small percentage of people) … I would tend to avoid using complex combinations of specifications to try and predict how a mattress will feel or perform for you. When you try and choose a mattress based on complex combinations of specs that you may not fully understand or only based on specs for single layers or components that may not be as relevant or meaningful as you believe they are then the most common outcome is “information overload” and “paralysis by analysis”.
Flobeds, SleepEZ, and Flexus are all members of this site which means that I think highly of all of them and that I believe that they compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency. All of them use high quality materials and there are no lower quality materials or weak links in any of them that would be a cause for concern in terms of the durability and useful life of their mattresses relative to any weight/BMI range and I wouldn’t hesitate to purchase a mattress from any of them. Forum searches on Flobeds (not Flowbed), and on SleepEZ and on Flexus (you can just click the links) will bring up many more comments and feedback about each of them.
You can see some comments about Plushbeds in post #2 here and a forum search on Plushbeds (you can just click the link) will bring up much more information and comments/feedback about them as well. They also use good quality and durable materials in their mattresses (natural or organic Dunlop and Talalay latex) and there are no lower quality materials or weak links in their latex mattresses that would be a cause for concern either and they would certainly be a much “better than average” choice compared to most of the mainstream mattresses that most people end up buying. They do a lot of internet advertising so they do attract a lot of online attention for those that are looking for a latex mattress but I would make some careful “value comparisons” with some of the other component latex options that are available to you because they may not be in the “best value” range for many of the members here that are aware of the many other similar options that are available to them…
Post #3 here also includes a list of many of the online manufacturers that sell component latex mattresses with loose layers and zip covers as well.
There is also more about some of the general differences between Dunlop and Talalay in post #7 here but the choice between different types and blends of latex in either the top layers or the deeper layers in a mattress is more of a preference and budget choice than a “better/worse” choice and different people just have different preferences. The best way to know which type or blend of latex you tend to prefer in general terms (again in either the upper or deeper layers) would be based on your own local testing or your own personal experience.
As you know latex and memory foam are very different materials with very different properties and both of them come in a range of different versions that each have differences in their properties and a different “feel” or firmness level but again the choice between them is more of a preference and budget choice than a “better/worse” choice. There is more about some of the general differences between memory foam and latex in post #2 here. Some people tend to prefer the faster response and more resilient and “on the mattress” feel of latex and some prefer the slower response and more “in the mattress” feel of memory foam and some people may prefer some combination of both of them. Once again the only way to know whether any specific mattress will be a good “match” for you (or both of you) will be based on your own testing or your own personal experience.
Both of the Christeli mattresses you mentioned also use good quality materials and there are no lower quality materials or weak links that could compromise the durability or useful life of either of them relative to any weight/BMI range either but once again when you can’t test a mattress in person then your best source of guidance about which of their mattresses may be the best “match” for both of you will be a phone call with Christeli. You’ve probably already dont this but a forum search on Christeli (you can just click the link) will bring up many more comments and feedback about them as well.
I would also keep in mind that Christeli has a 50 day exchange policy that allows you to make a single exchange for another mattress but they don’t offer a refund policy so if you don’t sleep as well on one of their mattresses as you hoped for then your only options would be to add a topper (if the mattress is too firm) or to exchange the mattress for another model that is either softer or firmer.
Unlike many innerspring mattresses … most foam mattresses (latex foam, memory foam, or polyfoam) don’t have a specific edge support system or even really need them as long as the firmness of the support core and the thickness of the comfort layers are suitable for your body weight when you are sleeping. Foam mattresses will generally feel softer and compress more deeply if you sleep with most of your weight concentrated on the very outside edges of the mattress or if you sit on the very edge of the mattress because your weight is more concentrated when you are sitting than when you are sleeping on the mattress. There is more about edge support in foam mattresses in post #33 here and in latex mattresses in post #3 here.
Having said that there are always exceptions and some people that either sleep with much of their weight concentrated on the outside edge of the mattress or that sit on the side of their mattress on a regular basis can certainly have a strong preference for a mattress that has a specific edge support system with any foam mattress.
You can see some comments about the type and quality of the materials in the Ghostbed along with many of the other what I call “simplified choice” mattresses in post #2 here and the first post in the same topic would also be well worth reading as well.
There are also some comments about the Purple mattress and the buckling column gel they use in post #2 here (they haven’t been added to the simplified choice list yet).
Forum searches on Ghost and on Purple will also bring up much more information and feedback about them as well.
Once you have narrowed down your options to a list of finalists that are all choices between “good and good” and you have confirmed that none of them have any lower quality materials or “weak links” in their design relative to your weight/BMI range and you have talked with each of them and there are still no clear winners between them (which is usually a good indication that you have done some good research) then you are in the fortunate position that any of them would likely be a reasonable choice and post #2 here can help you make a final choice based on any local testing you have done, your more detailed conversations with each of the online options you are considering, your personal preferences, your confidence about PPP and the suitability of each one, their prices, the options you have after a purchase to fine tune the mattress or exchange or return the mattress (or individual layers in some cases) and any costs involved, any additional extras that are part of each purchase, and on “informed best judgement” based on all the other objective, subjective, and intangible parts of your personal value equation that are most important to you.
Phoenix