I have a couple of B acetylene tanks and a Prestolite torch. Great for plumbing and brazing small stuff. Bigger things I use oxy-acetylene. With oxy you have to watch your heat or you'll melt the base part!
Remember the plumber coming in and watching him working and noticing how fast he could sweat pipes. He had a B tank of acetylene. I immediately switched over from propane and haven't looked back. Soldering with acetylene is so much faster. Sweating pipes is pretty easy. Dry the pipe, clean the fittings, flux it and heat the coupling - solder just wicks in with a nice ring all the way around. It gets more fun when water has been there, but there's work arounds.
Major downside for acetylene is cost and you do have know to limit the flow rate from your tank. In practice that means no huge rosebuds on tiny tanks. Drawing too much flow from a tank can cause the acetone to be drawn from the tank which ruins the regulator and the acetylene can become unstable. Both can be hazardous. Like all the "toys" we deal with, we need to know how to handle them safely. Same with acetylene. Last fun fact, acetylene has a very large explosive range when mixed with air. This makes leaks quite hazardous. I believe the explosive limit range exceeds that of natural gas.
