Every technique has its risks;
Reg inflation; catching the reg and getting yanked up, or freeflow.
Suit feed; The feed jamming and getting yanked up
Crack bottle; they do sometimes jam shut (lack of maintenance), and they're bulky.
Exhaust bubbles; catching the reg and getting yanked up
Like anything, you can train to minimise the risk, lets not over emphasis
The crack bottles are nice for speed, but to be honest, I go for exhaust bubbles. Its quick, easy... and balances your bouyancy against that of the bag.
Anyone wanna buy a crack bottle DSMB? :P
/Z