Hi jm20w,
Some people prefer a quilting layer (usually either natural or synthetic fibers or polyfoam) above the latex layers (see post #12 here) but this has 2.5" of polyfoam above the latex which as you remember reading is more than I would normally like to see. I normally use a guideline of no more than “about an inch or so” of lower quality/density foams or materials in the top layers of a mattress so this is more than the guideline. Once you are at about 2" or more then it can become the “weak link” of a mattress so I would want to know the density of the polyfoam layers in the top 2.5" to make sure that they are durable materials (I would use 1.8 lb polyfoam as the minimum density for layers that are 2" or more and higher density yet may be a good idea for higher weights). The other latex layers are all Talalay latex (probably blended Talalay) which is a high quality material. Some of the Therapedic licensees use thicker layers of polyfoam above the latex in their mattresses and others don’t. This would be a “mostly latex” mattress.
Convoluted means that the foam is modified like an egg crate (see here). There is more about the effects of convoluted foam in post #2 here. In general it would be less durable than a solid layer but would also have a softer “feel” than the same type and firmness of foam that wasn’t convoluted.
The first step here would be to make sure that the top 2" were also 1.8 lb polyfoam or better. If it is then the 2" of 1.8 lb density polyfoam would be at the bottom of what I would consider to be good quality polyfoam in a one sided mattress (unless someone is heavier in which case I would use about 2.0 lbs as the minimum guideline) so for “average weights” (and assuming again that the top 2" is 1.8 lb density) this mattress wouldn’t have any obvious weak links although it uses only fairly thin layers of latex (and they don’t mention the type or blend of the latex which I would also want to know) so it should be in a lower price range than a mattress that uses more latex. This would be a “latex hybrid” mattress (that only uses latex in the comfort layers).
You can read a little more about the difference between an “all latex” mattress and a latex hybrid mattress in post #2 here.
I would make sure that you do some careful and objective testing to make sure that any mattress you are considering is a good match for you in terms of PPP. The suitability of a mattress for your body type or sleeping style is not something I can know based on “theory at a distance” (see mattress firmness/comfort levels in post #2 here). As you will read in the tutorial post and the other posts it links to … the showroom feel of a mattress is among the worst ways to choose a mattress. Comfort/pressure relief is what you feel when you first lie on a mattress, Support/alignment is what you feel when you wake up in the morning (with or without back pain or discomfort), and the durability of the materials … especially in the top layers … is what you will feel down the road when lower quality materials soften or break down faster than they should which can result in the premature loss of comfort and/or support in a mattress. You would need to make sure that a mattress is a good match for you with all three.
I would certainly be very careful about choosing a mattress that is too soft because of the risk that you will be sleeping out of alignment. You can make a mattress that is too firm softer with a topper but you can’t make a mattress that is too soft (with either comfort layers that are too thick/soft or support layers that are too soft) without removing and replacing foam layers or replacing the complete mattress.
My previous comments would apply here as well and I would definitely want to make sure that you know the density of all the layers in the mattress. Even though they don’t provide any comfort specs (which are often proprietary and not necessary to know) … this mattress certainly looks like it would be very soft.
This mattress also has a pocket coil system for the support core so it wouldn’t “feel” the same as a full latex mattress and with 2" of soft polyfoam above only an inch of latex the comfort layers would have more of the “feel” of polyfoam than of latex.
Ouch … it’s one of the few times that those of us in the Pacific Northwest were smiling about how good we have it instead of complaining about the rain 
I’m not sure of the reasons for the exchanges but if they were for comfort reasons then being allowed to exchange more than once would be quite generous (most stores won’t allow more than one). Of course if it was a warranty exchange then this would be something different. It’s always better to test a mattress as if you only have one chance to make the right choice and to test very carefully for PPP and make sure you know the quality of the materials and this will greatly increase the odds that you won’t have to make an exchange. Of course nothing is perfect and mistakes are always possible in which case any return or exchange policy may be worth the extra cost it adds to the cost of a mattress (the people who don’t exchange a mattress pay for the ones that do) and this would be part of your personal value equation.
Yes it’s an airbed. You can see my thoughts about airbeds in this article and in general I would suggest avoiding them.
Phoenix