I've got a question that I think is along the same lines as the discussion in this thread. So here goes. I'm still diving wet, fairly new diver. I started diving tropical after my certs and was pretty confident that I got my weighting and buoyancy control figured out. In G. Cayman, using my 9# BP/W, AL80 and 3mm shortie I was diving 3# on my belt and using lungs to control my buoyancy throughout the water column. My diving became SO much easier. A real pleasure. I then start diving local in RI in my 7mm, 9# BP/W and steel tank. I was amazed at how buoyant this 7mm is in saltwater, even in fresh. On one dive I was several pounds underweighted and even after I kicked down to around 10 feet the suit compression started to become evident. I really didn't notice the 7mm compression issues during OW and AOW dives as I was most likely overweighted at this time anyway and not that deep. Even being underweighted or properly weighted I'm amazed at the amount of air I need to add to my BC to offset the significant compression. Nothing like diving the 3mm shortie. I understand the benefits of drysuit diving to keep warm, but will the buoyancy swing be minimal compared to a 7mm? I assume the non-compressable suits like the DUI TLS series are the way to go. I'm guessing that the extra weight required couldn't be that much more than my 7mm?