Hi GranolaKure,
You can read a little more of my thoughts about the differences between an all latex mattress and a latex/polyfoam hybrid in post #2 here.
The Alexis would be in between and I would personally choose a latex transition or middle layer over a polyfoam transition layer particularly for heavier people who would “go through” the upper layer and compress the middle layer more but I would also choose an all latex mattress over either if I could comfortably afford it even though it’s also true that the deeper the polyfoam layer is the less effect it will have overall on both performance and durability. The Alexis also has two layers that can be either re-arranged or exchanged after a purchase.
As in so many things connected with mattresses … It’s really a matter of the tradeoff between budget and performance and on each person’s personal value equation. Both would make great choices IMO.
Phoenix