How did you find the gravity feed worked?
I've had a gravity feed Bear Cat for over 10 years. It works very well for me. People who do chipping for a living need mechanical feed, but for most of us it's a waste of money and maintenance effort. Gravity feed takes longer, but if you are only using it a few times a year to clean up newly-gathered brush it's perfect.
There are two classes of chippers, those that chip primarily 2"+ material and chippers that shred leaves and branches. One
chipper will not do both tasks well.
I don't know what you mean by two classes of chippers. Chippers don't do very well with leaves and small (under half inch) brush. That's what shredders are for. If you need to do a lot of small stuff you need a
chipper/shredder. If you only do a little of that a
chipper will do.
The problems with chippers are two: clogs and maintenance. Clogs have to do with above.
I've never had a clog in my
chipper in all the time I've owned it.
Maintenance has to do with maintaining blades sharp. PTO chippers have from one to four blades. Better chippers have four. The blades need to be removed periodically from the heavy drum, which is difficult, then sharpened precisely, perhaps 12" of edge for four blades, then reinstalled and adjusted. (Sharpening requires precision. There are several services that sharpen vis US mail or a machine shop can do the sharpening and honing.)
THIS IS A LOT OF WORK.
Removing the blades isn't difficult if you buy one that offers reasonable access to the flywheel. My Bear Cat requires me to remove one bolt and swing the output chute to the side. The blades are then exposed and then can easily be removed with a socket wrench. The only "difficulty" is I sometimes have to dig out the dirt or whatever that collects around the head of the bold with a small screwdriver.
My old
chipper/shredder was a pain to sharpen the blades. You had to take off the top of the shredder chute to access the blades. There were lots of bolts, some hidden behind the belt guards, and the part you had to take off was heavy and awkward enough to be pain to remove.
The blades do have to be very sharp to self-feed. They still feel sharp to the touch when they are too dull to self-feed. I have a Tormek wet sharpening system that holds them at a fixed angle that makes sharpening easy. My blades, like many, are sharpened on both sides, so you only have to sharpen them every other time; in between just turn them around.
Getting one with a blower is really worthwhile. My first
chipper/shredder didn't have one and I had to stop and clear the chips out from under it every few minutes. A blower also helps when using it to do spring cleanup of fallen branches - just point the chute at the woods and let the chips fall where they may.
Having one handy of occasionally work throughout the year is the best reason to own rather than rent one in my view.
