I had to have a portable one. I did buy big once (if 20 gallon is big)
until it got stolen from the job site. I had to move from floor to
floor for the finish work (3 floors), so this one has definitely served
its purpose. I thought about an air wrench, but if it would be corded
anyway, I use my big drill with a socket driver on it and get tons of
torque. Now that I'm in a "stable" mode, I have to decide whether to
upgrade to a larger one and I would rather spend the money on a
jointer, DC, TS, etc.
It was the same thing with my tablesaw. Yeah, it was a $100 skill saw
that is pretty much only good for basic ripping, but operating on 3
different floors its easier to to relocate it that way rather than
hauling stock all over the place. This saw served its purpose. Some of
the portable tools I bought were very nice. I bought the barrel grip
bosch jig saw (awesome), the bosch power planer, and the Bosch
1617EVSPK 2.25 Horsepower Electronic Variable Speed Plunge and Fixed
Base Router Kit.
You can see pictures of the interior finish work me and my brother in
law did at: www.astutesolutions.net/cabin.html. The exterior work was
not done by me.