I do a lot of chipping (thus the name). One thing that I was warned about decades ago has proven very true; a lower-to-the-ground (and lower-angle) feed chute is critically important. The more you have to lift and "angle up" branches, the less you'll be able to do in a day.
We chip a lot of fir branches, especially after storms- some are 15, even 20' long. With a low feed chute, I can get the butt end up and into the machine, then walk away as the branch is pulled through.
Our
chipper is a Valby CH150; I bought it in the mid-1990's, and am completely happy with it.
Valbys are made in Finland; while not cheap, they are VERY heavy duty, with first-rate bearings, welds and etc. The cutter knives are extremely beefy hardened steel. When needed, the dealer sharpens the knives cheaply and quickly - we just mail them!The chute outer edge is roughly 1' off the ground. The discharge chute is steerable- you can make a pile anywhere, or just spread it into the woods. We use all of ours on trails.
I did not opt for the hydraulic feed roller; I could not afford one at the time of purchase, and my original tractor did not have remotes. While I would still like to have one, the machine works very well without it.
I now use a 50hp tractor to power mine, but a friend has the same
chipper and powers it just fine with a 25hp tractor.
Used ones do come up for sale; our dealer, in southern Oregon, moves a lot of them, new and used.
(Envirochipper Industries, Gold Hill, OR)