acetylene torch

My small repair shop I have been using a bernzomatic torch using mapp gas. I have been getting by with it, but there are times I just can't get enough heat from it. Also I would like to do some small brazing jobs at times. I know bernzomatic makes a set like that but uses mapp gas instead of acetylene. Has anybody ever used one of these bernzomatic sets and if so how do they work? Just how long dose the oxygen tank last on the bernzomatic set? My next choice is the local welding supply store has a small complete acetylene torch set including full tanks for only 319 dollars which I find is a very good price. I haven't decided which way to go because either set would get very little use.