Hi Strat,
Welcome to the Mattress Forum! 
Just in case you haven’t read it yet … the first place I would start your research is the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that you will need to make the best possible choice … and perhaps more importantly know how and why to avoid the worst ones.
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” and PPP (Posture and alignment, Pressure relief, and Personal preferences) 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).
[quote]The two main mattresses I think I’ve narrowed it down to are:
eLuxury/ExceptionalSheets 10" Gel Memory Foam Mattress ($445)
www.amazon.com/dp/B00QSEK2Y6[/quote]
A forum search on eluxury (you can just click the link) will bring up some comments and feedback about them and as you can see some of their online descriptions are misleading and I wouldn’t consider them to be a reliable supplier. In addition to this I would consider 3" of 3 lb memory foam in the top layers of a mattress to be a weak link in a mattress which I would avoid (see the quality/durability guidelines here).
[quote]Perfect Cloud Atlas Gel-Plus 10" Memory Foam Mattress ($450)
www.amazon.com/dp/B00KSL9T3U[/quote]
Outside of confirming that a mattress is a good match for you in terms of PPP (or making sure that there is a good return/exchange policy if you are uncertain) ,… the most important part of the value of a mattress purchase is the quality and durability of the materials inside it (regardless of the name of the manufacturer on the label) so I would always make sure that you are able to find out the information listed here so you can confirm that there aren’t any lower quality materials or weak links in any mattress that you are considering. This includes the density of all the layers not just the top memory foam layer.
They also don’t appear to be particularly knowledgeable about the materials in their mattresses because in one of the questions on Amazon they were asked about the foam density of the other polyfoam layers and they replied that it was 3 lb density which is almost certainly wrong (and it also wouldn’t match their shipping weight).
Dura Global is also just an import and marketing company that imports many types of products and they certainly don’t specialize in mattresses. I personally wouldn’t have a great deal of confidence that any guidance they would provide when you talk to them on the phone about whether the mattress you are considering would be a suitable choice for you (which I would consider to be an important part of any online mattress purchase) would be reliable.
They are also fulfilled by Amazon so if for some reason you purchase one of their mattresses that doesn’t turn out as well as you hoped for then you would be subject to the cost and time limits of the Amazon large items return policy (see post #11 here).
There is also more about purchasing a mattress that is made in China that may be subject to longer periods of compression during shipping and storage and some of the additional risks and uncertainty that can be involved with this type of purchase in post #6 here.
While other people’s comments about the knowledge and service of a business can certainly be helpful … I would be very cautious about about using other people’s experiences or reviews on a mattress (either positive or negative) as a reliable source of information or guidance about how you will feel on the same mattress or how suitable or how durable a mattress may be for you and in many if not most cases they can be more misleading than helpful because a mattress that would be a perfect choice for one person or even a larger group of people may be completely unsuitable for someone else to sleep on (see post #13 here).
The tutorial post includes several links to some of the better online options I’m aware of (in the optional online step) that includes many different types of mattresses in a wide range of budgets that would be well worth considering if you are looking at online options but I would consider both of the mattresses you are considering to be somewhat risky choices.
If you let me know your city or zip code I’d also be happy to let you know about the better options or possibilities I’m aware of as well.
Phoenix