Hi wbabbit,
You have the specifications of the product and are able to compare them 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 (which we’ve already done).
Just in case you haven’t read it yet, the mattress shopping tutorial here includes all the basic information, steps, and guidelines that can help you make the best possible choice (online or in-store), and perhaps more importantly help you 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 (both 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).
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 manufacturer that has your best interests at heart who can help “talk you through” the specifics of their mattresses and help pick which comfort level 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 well on and liked that they are familiar with, any special considerations you may have, and the “averages” of other customers that are similar to you.
A good online retailer or manufacturer will generally make suggestions that they honestly believe have the best chance of success based on the information you provide them when you talk to them on the phone because this is in both your own and their best interests, but at the end of the day the only way to know for certain whether any specific mattress is a good match for you in terms of comfort, firmness, and PPP will be based on your own careful testing and/or your own personal experience. You’ll also want to learn about the options you have available after a purchase to either exchange the mattress or return the mattress for a refund (and any potential costs involved – I think they arrange for your mattress to be donated), and this information would generally become a more important part of your personal value equation just in case a mattress you purchase doesn’t turn out as well as you hoped for.
The choice of using polyfoam, springs, or latex for a support core is purely one of individual preference. Post #28 and the links contained within it talks a bit about latex versus springs.
Phoenix