I have an HD-8, with full hydraulics, and love it..!! If you get one, make sure you get the one with the hydraulic tilt. You'll tilt it more than a person would realize, mostly fore and aft, especially when you drop the 3 pt. You'll need to tilt the top towards the tractor a bit, every time you drop the 3 pt. I drove close to 400 posts by myself, through an open winter here. Cold, but not enough to freeze more than just a crust. Clay soil was good and damp, but not muddy. It drove the 5" round line posts pretty easy. The 6" corners took a bit longer, but still drove them pretty easy considering.
It is a lot easier to have a helper, if for nothing else to line up posts, and position the tractor. If I drove 25 posts a day, I considered it a good day through the winter, with short daylight hours. But, I was pretty particular having posts in line. Very few times, I was right on the money getting in position. Even with a string strung, always seemed to have to move just a tad. So roughly 70 times a day on & off the tractor is rough on an old guy.
I kept a small torpedo level in my pocket to keep the posts plumb. If it would drift one way or the other, you can use the hydraulic tilt, to bring it back, hitting it a few licks, to straighten it up.
Pipe should drive pretty easy, but myself, I'd probably have to think of putting a wooden headblock in there of some sort, to possibly prevent chunks of pipe breaking off, and flying.