I have one of these for home use:
We also use the pitbull injector for comps, vending and catering. Mostly for larger cooks. It wouldn't be practical for just one butt since the intake tube holds so much injection, there would be a lot of waste. It sure is awesome for cooking multiple butts. This one, also, cannot be used when the injection has any solids in it or it will clog....BAD.