Yes, I agree, that is what I was saying also. I just wonder if the human body doesn't also change buoyancy with depth, making neoprene density variation pretty negligible by comparison.

From what I understand, no. The only thing that compresses is the air inside your lungs, but you keep on breathing in & out pressure compensated air, so the buoyancy difference doesn't change as you go down. Neoprene compression has a fairly large effect, pounds worth of buoyancy. Look at this spreadsheet for example, at depth you lose 11.6 pounds of buoyancy due to the neoprene compressing: https://www.scubaboard.com/community/threads/the-ultimate-wi...