Hi Pegabo,
You can see my comments about gel materials and temperature regulation in my reply in post #10 here.
I would need to know the density of the aqua gel to be able to make any meaningful comments about the durability of the material or the mattress as a whole (see the quality/density guidelines here).
There could be many reasons for this which could include that they may believe that they don’t need that many ILD’s to design different mattresses that would be suitable for the majority of their customer base (they could use layer thickness instead of layer firmness for example or different combinations of materials to adjust the softness/firmness of their mattresses) or they may not wish to carry that many different ILD’s in their inventory or believe it’s necessary (which of course would involve some costs), or their preferred supplier may not have the full range of ILD’s available (and other suppliers may be more costly). These are really questions that only they can answer though.
Phoenix