scubafool:If you need to let ALL of the air out of your BC to start your descent, then you need more weight.<snip>
Anyhow, just about the only time I dump ALL of the air out is the last 3 or 4 feet of my ascent when I am diving single tank & I have spent a lot of time shallow breathing the tank down to 300-400 PSI.
This was my contention....