Hi CW926,
Well I believe you 
It’s actually only the latex comfort layer(s) that are split so you can each choose your own comfort level. The support core isn’t split. You can read more about split layers in post #2 here but with a suitable tight fitting quilted cover (which both mattresses have) you will feel the difference in firmness on each side (which is the reason for the split) but you won’t feel the actual split itself.
There may be some latex mattresses in your area that you can test latex to get some sense of how it feels and responds (although there are many different firmness levels and designs that each have a different “feel”) but latex is the most resilient of all the different types of foam (latex foam, polyfoam, and memory foam) so it has a more “on the mattress” feel and less motion restriction than other foam types (especially memory foam which has a slow response and is more motion restricting). You can read more about the difference between the fast response of latex and the slow response of memory foam in post #2 here. If you let me know your city or zip code I’d be happy to let you know of any options in your area I’m aware of that may carry latex mattresses that you can test.
Phoenix