Hi suprattmike,
[quote]So I think I’ve narrowed down my decision to a Talalay Latex mattress. I’ve picked 3 vendors from the Membership list.
Arizona Premium Mattress Co (AKA Mattress.net)
Latex Mattresses On Sale - Latex Mattress Toppers - Phoenix, AZ
The Original Mattress Factory
www.originalmattress.com/latex-foam/overview
Brooklyn Bedding (AKA Dreamfoam Bedding)
www.brooklynbedding.com/latex-mattresses...total-latex-mattress
www.amazon.com/Ultimate-Dreams-Queen-Tot...tress/dp/B00AAL0HNY/[/quote]
These are all good quality and value options but for the sake of clarity I should mention that The Original Mattress Factory is not a member of this site (you can see the membership list here and the members that sell online are listed here). I would only consider them if you are local to one of their stores and can test the mattress in person because they are not set up to do layer exchanges and don’t ship their mattresses by courier so shipping costs will be higher.
You have certainly eliminated your worst options and have narrowed down your options to final choices between good and good.
I can only speak to the quality and value of a mattress and help the members here identify any weak links in terms of durability and all of these are good value in their price range and have no obvious weak links. This means that you have reached what can be the toughest part of the process which is choosing a mattress between “all good” options where there are no clear “winners” and all the objective, subjective, and intangible factors that are part of every mattress purchase and that are uniquely important to you are the only meaningful basis for a decision. In terms of quality and value there are no “mistakes” left any more 
Post #2 here has more about making final choices when all your remaining options are good ones and the only meaningful differences are the ones that are most important to you.
Some of the things I would consider are your confidence in the suitability of each mattress in terms of PPP and the options you have after a purchase in terms of layer exchanges or a mattress exchange and the costs involved if your choice is less than ideal. I should also mention that the Total Latex Mattress from Brooklyn Bedding and Amazon is the same mattress at the same price but the return and exchange policies are different (Brooklyn Bedding is less costly).
I like them. They can exchange the support core of the mattress on each side which means that you can also affect the “feel” and pressure relief of the upper layers (all the layers work together). The differences between the methods used to adjust comfort and support and the options available are part of each person’s personal value equation and some of the manufacturers here have more options to make changes than others. For some this is a benefit and for some it’s less important. With this mattress you can exchange the firmness of the support core which affects the “feel” and pressure relief as well. I personally like mattresses that provide the ability to make adjustments at a reasonable cost after a purchase.
This will have a more direct effect on the pressure relief of the mattress and a secondary affect on support/alignment.
There is no better or worse … they are just different. Adjusting the comfort layer will have more of an effect on the feel and pressure relief of the mattress while adjusting the deeper support layer will have more of an effect on support/alignment. It depends on the type of adjustment that you may need. Both of them have the ability to choose different support layers prior to the purchase. All the layers of a mattress affect the feel and performance of every other layer but changing the deeper layers has more of an affect on alignment and primary support (the type of support that “stops” the heaver pelvis from sinking in too far) while adjusting the comfort layers will have more of an effect on pressure relief and secondary support (which fills in the recessed gaps in your sleeping profile). Some of the members here sell mattresses where both the comfort and support layers can be re-arranged or exchanged and have more flexibility yet but may also had additional cost.
The convoluted Talalay is blended Talalay. Convoluted foam is like an egg crate foam (see the picture here). Convoluting will change the response curve of the foam making it softer on top where there is less material and then getting firmer faster as you sink into the thicker parts of the hills and then into the part of the layer that isn’t convoluted. In technical terms it increases the compression modulus (the rate at which a foam gets firmer as you sink into it). The shape and depth of the convoluting are used to change the response curve of the material. Convoluted foams have less material (you can make 2 convoluted 2" layers out of a single 3" layer for example) and are less costly and would be less durable than the same ILD layer that is a solid material but the OMF mattresses are also two sided which increased durability. Durability wouldn’t be an issue with any latex mattress because it is the most durable of the foam materials. Any foam (or type of latex) can be convoluted to change the feel and performance of the mattress.
In an apples to apples comparison between two mattresses that use the same materials of the same type and softness/firmness level … a two sided mattress will be more durable than the same one sided mattress because the layer on the bottom has a chance to rest and is compressed more evenly and much less than the layers on the top which take up most of the wear and stress from sleeping on them. The softening of layers under the heavier parts of the body is the biggest reason for loss of comfort and support and this would reduce the softening of the areas under the greatest stress … even in a material as durable as latex. The tradeoff with a two sided mattress is that there is less flexibility of design because you can’s use thicker layers or more sophisticated progressively firm designs because if you have too mush soft foam on the bottom of the mattress (the support layers) you risk alignment issues. With a mattress that has a replaceable top layer you can also replace just a single layer if it softens or breaks down faster than the deeper layers of the mattress without having to replace the entire mattress.
In a single word no (if it was they would certainly have changed their designs over the many years they’ve sold them). The thickness of a layer, the softness of a layer, the quilting of the mattress, and how all of these interact with the layers below all affect the feel and pressure relief of the mattress. With thinner top layers then the firmness of the upper part of the layer below becomes part of the comfort layer. All of this is part of how mattresses are designed in different ways and here are many pathways to the same end result in terms of PPP. A mattress that uses a two inch comfort layer over a softer support core can be very similar to a mattress that uses a 3" comfort layer over a firmer support core for example if the top 3" of the mattress are the comfort layers for a particular person (each person will have a different depth of cradle which is their “critical zone” for pressure relief).
Hope this all helps and when you are down to final choice I would make sure that you compare all the different factors that are part of every mattress purchase which of course includes price, type, quality, and amounts of materials, the options available to make adjustments before and after a purchase and the cost involved, and all the other factors that have “value” and are important to you.
Phoenix