I am a bit late on the thread, but I got one of these last year. My place is 11 acres that was last bush hogged around 20 years ago. The grubber works great on patches that are a bit too big to hog, but small enough to bend over easily. If you have help, it is a bit faster than wrapping a chain, but you have to take off slow and steady instead of snatching it out fast with a chain. If you start to fast, the grubber will slide right off a tree.
I used it for a while this fall, with my wife pulling with the tractor and me slinging it around. I eventually took it off because I could chain several small trees and snatch them out at once. A good tool, but I wouldn't spend the money to buy another if I broke it.
I usually just bend the small trees over and pop the roots out by curling the bucket, but snatching them is a lot less messy on the dirt.
Joel