Hi Passat,
Unfortunately … there are too many unknowns, variables, and personal preferences involved for anyone to know which mattress is best for you based on a formula or “theory at a distance” or that can predict this more effectively than your own personal testing and experience (see mattress firmness/comfort levels in post #2 here). Nobody else can feel what you feel on a mattress.
I would make sure though when he does his testing that the Beautiful keeps him in good alignment in all his sleeping positions and that the Nature doesn’t have pressure points for you. The Nature would be closer to a “happy medium” in terms of its rated softness level (the Beautiful is much closer to the soft end of the range) but each person can be very different from someone else.
Phoenix