Check out Ultimate Air. They are easily as good as Powertank, cheaper, and the owner is about as nice a guy as you'll ever meet. He will bend over backwards to make you happy about your purchase.
As far as tanks themselves, they are faster than compressors, and you can run tools of them and such. The problem is when on the trail, people who don't have air always want you to share. They apparently don't realize you have to pay for the fills, and it will run out. I personally have a bottle and a compressor. I won't always break out the bottle when I'm around a bunch of people I don't know. I will just use my compressor. I don't mind sharing, but filling it after every outing gets real old and expensive.
Last edited by oz97tj; 08-02-2009 at 09:51 PM.