I just got the Kitchenaid grinder a little while ago, and I've only used it once -- I'm planning to get serious about bread, but only planning -- so take this for what it's worth.
It's solidly made and relatively simple, not hard to figure out. A hopper feeds the grain to a screw, which pushes the grain to the grinding plates.
It did seem slow, but I don't have anything to compare it to. I ground about three cups of hard white wheat berries, and while I didn't time it, I'd be surprised if it weren't at least ten minutes.
It says that you shouldn't grind more than 10 cups at a time. You need to let it cool off after that.
No nuts, coffee, or other oily stuff.
The quality of the ground flour seemed good to me.
