I never noticed a difference. I was a 32G when I started diving again after my second baby. (I was nursing), and when I stopped I went back to a 32D. G's are huge. I wear a 10 pound weight belt, instead of it all intergrated. I didn't wear a weight belt last weekend (had to sacrifice the smaller weights for underweighted students) so I wore all 30 pounds intergrated, and I have to say I had a harder time with buoyancy and trim, even tho the weight was the same. One of my buddies recently had a reduction, she hasn't mentioned specific buoyancy issue, just generally more comfortable in her gear.