Hi eeks,
A mattress with a polyfoam support core (regardless of the material in the comfort layers) will generally do best with a firm, flat, and evenly supportive support surface underneath it that has minimal to no flex under the mattress and for larger sizes with at least one center support beam that has good support to the floor to prevent any sagging in the middle of the mattress. The components (either a bedframe and foundation or a platform bed) need to be strong and durable enough to support the weight of the mattress and the people sleeping on it without some of the parts bending, sagging, shifting, or breaking with extended use. The support surface under the mattress (which may be slats or a solid surface or a steel or wire grid) should have enough surface area to prevent the mattress from sagging through any gaps or spaces in the support surface over time but still allow some airflow under the mattress. If a foundation or a platform bed has a slatted surface then I would suggest that the gaps between any slats are no more than about 5" (with 1 x 3 slats) although less than 4" would be better yet.
With an all latex mattress then I would suggest gaps that are no more than 3" and once again less would be better yet.
There is more information about support systems (bedframes and foundations or platform beds) that are generally suitable for different types of mattresses and some examples of each of them in post #1 here and some of the information and comments in this topic may be helpful as well.
The Brooklyn Bedding simple life foundation has a wire grid as a support surface (see post #10 here) and the SleepEZ foundation has wood slats that are less than 3" apart. While either one would be suitable for a mattress with a polyfoam support core … the SleepEZ foundation would be more suitable for an all latex mattress because there are less “gaps” in the support surface.
Phoenix