Hi Maia,
As you may expect … I completely agree that compared to “S” brands … almost all local manufacturers have much better value when actual materials are compared and of course the better ones like SleepEz have even better value yet. There is no comparison between manufacturers like SleepEz and the typical chain store mattresses or major brands. I just wish that more consumers knew how little they were getting for their money. Don’t forget too that your membership here gives you an additional 5% off which saves you an extra $120 
The “gel memory foam” comes in different types and depending on the density and type would be comparable to memory foam in terms of durability. The ones that use particles will be less durable and the ones that infuse the gel will strengthen the memory foam matrix and they will last longer. There’s a little more here about the different types of gel that are being used in post #26 here. The “pure gel” (not to be confused with the gel infused in memory foam) is one of the most durable materials but it’s also much more expensive than latex. An example with a 1" gel layer is here.
Their latex mattress line is made by Ecosleep (but have a different name). They are the one sided versions and they can be “better than average value” depending on the outlet that is selling them.
My notes from some time ago (over a year) say that they also carried Vivetique but I haven’t been to their site in a while so I don’t know if that’s still correct or if they make their their latex futons. The specs on the futons don’t quite add up (the specs would indicate a mattress thicker than 9") but I believe that it has 6" of latex in it. They would be much firmer and have less “range of compression” than the 13000 because there is less latex, firmer cotton which would reduce the compression of the latex, and the type of layering you can use in a two sided mattress is more limited than a one sided version although any two sided mattress will add to durability. Cotton will compress to about 50% or its original thickness and become firmer as it compresses. Overall though they use very good materials and they have reasonable prices IMO. If I have a chance I’ll call to clarify the specs and update my notes.
It’s almost certainly Dunlop (which is all that Vivetique uses ). In general … if it doesn’t say Talalay or if it says all natural without mentioning a type … then it’s almost always Dunlop.
They are not in the same value range as SleepEz but they would certainly make a better choice than many other outlets. You have the best of both worlds … the ability to test the mattresses in person (which is more accurate) and local manufacturers with online pricing and value that are among the best in the country. If I was looking for latex I personally wouldn’t be looking anywhere else besides locally.
Phoenix