If you're planning to use it for asphalt shingle roofing, you might want to talk to a roofing outfit first.
There's an outfit here that is fast, good and reasonable- probably do 80% of the roofing in this area. I got a new roof last summer, and was surprised that they were using hammer and nails, instead of air staplers. Asked the guy, and he said they had tried them, but there was no way to do a good job with them. Penetration of the staple depends on the air pressure, and the pressure would first be too high, resulting in staple going all the way through, then just right, then too weak and staple had to be hammered down. And when shingles were hot and soft, even worse.
They were amazing- 35 square job, 2 layer tear-off. 8 or 10 guys, as I recall- they got there at about 7:30, and when I came home at 4:30 they were done and gone, and it was hard to find any evidence that they had ever been there.