think of it this way if your car breaks down you eventually roll to a stop brakes dont work use e brake its a cable or your gearing to slow down.. if gas leaks its usally not a big isuse untill it vaporizes and comes into contact with a open flame.. basicly if your car brakes you are more likly to surivie it if you are at 100 feet over weighted and then your bc gives out and you become negative boyenet you have a problem and if you ditch your weight you then become postivly boyent.. its about haveing gear for when you need it and wanting it to work with out anyproblems if the patch blows out at depth and you become sinking you ditch your weight then you start floating up its going to be hard to do your safty stops if you have to swim dowards each time.. i bought my own for the simple reason.. how much is my life worth to me.. 100 200 300... its worth alot more then cheaping out and not replaceing something thats broken and may not be relable..
think of it this way its not a mater of if its not consider a life saveing flotation device if its keeps your head above water when you need it to it can save your life.. it shouldnt be used as a subsatute but if its an emergancy i rather have something that floats then nothing even if you will float with not weight its alot easyer if you are in something keeping you up