Hi JennK,
I think this would be particularly true with a slow response material like memory foam and a fast response material like latex. It may still be worth the compromise though depending on how strongly each of you feels about your favorite material. If it was an issue where the benefits didn’t outweigh the downside … you would at least still have the option of changing one side to the same material as the other.
As Sleepy1 also mentions … there are many different versions and layering combinations of latex (or a topper in her case) that can have a different “feel” and this may be part of it as well. It may be worth seeing if there is a dealer near you that sells Pure Latex Bliss (they have a retail finder here) and they sell very soft latex toppers which can be added to most of their mattresses (although in some cases this could lead to a comfort layer that was too thick and soft for best alignment).
Since you mentioned West Chester … some of the better options I’m aware of in the area (assuming you didn’t have to travel far to go there as well) are listed in post #2 here which should give you some more testing options.
And of course feel free to let us know how things go.
Phoenix