We use a Vermeer 935. Ours has a 50 HP Perkins Diesel, its a 2000, with auto feed II. It works great. The autofeed didn't seem to be working right when we bought it. It doesn't always stop the roller soon enough when it is getting bogged down. But ours will take 9 inch logs (minus big knots) no problem. It has about 1300 hours on it. We pull it behind a chevy one ton with a dump box, and if the box is full of chips someone usually has to spot me when I am backing up b/c you don't catch it in your side mirrors until you're already turned to sharp. But, you get used to it, its really not too hard to back up/handle.
Don't quote me on this but I think our unit (with the perkins) weighs about 4000. Definitely make sure the electric brakes work on it. We didn't have ours set up when we first bought the chipper and we can fit about 2.5-3 tons of chips in our box, pulling that kind weight, we trashed the rotors on the front end of our one ton, and the way most one tons are designed, the rotor and wheel hub is all one assembly, so it was expensive to fix. Not too mention if you're driving in rain or snow you don't want that thing pushing on you when you stop.
I would reccomend the 935 to anyone who keeps wood 6 inches and bigger for the wood pile, its a workhorse. Keep the knives sharp, and make sure the sheer bar is set as close as possible to the knives and it will make really nice small chips- when we have a box full of the right stuff we usually come across someone on the block where we are working who wants the chips for their garden; which saves us time and money.
What is the price set at?