Hi ehuesman,
I don’t think you would be giving up much if anything in terms of durability with the phase change gel they add (assuming equal ILD’s) and it would be very similar to the Talatech in terms of durability (although I haven’t seen any specific testing comparisons about this). The main benefits of the phase change gel is that it may make a small difference in temperature regulation but Talalay latex is already the most breathable foam category and temperature regulation is usually not an issue. Once temperatures have evened out as well, all foams will become insulators to differing degrees so phase changing technology is not as long lasting in terms of temperature regulation as ventilation (see the end of post #4 here). I think that the main reason that the phase changing gel was added was for competitive reasons to make it more easily comparable to the gel memory foams that are so common. The down side of course is that it costs more.
I would also bear in mind that ILD differences this small may be below the ability to detect for most people or would be less than the normal variations in the material itself (ILD variations across the surface or differences in the average ILD of different layers in each material). I would also keep in mind that 100% natural Talalay is a denser material and is not quite as pressure relieving as the blend (you don’t sink in quite as far) and has a higher compression modulus so a little higher ILD in the blended may be a little closer to equivalence if the ILD’s were exact and consistent across the surface of the layers (which they aren’t).
As far as I’m aware … LI and Radium both use a 30/70 blend.
Phoenix