Here's my two cents.
I have a friend with a 3 point stump grinder, I don't know the manufacturer, but it is quite effective. It is hard to judge how far back into the stump you are going to cut when looking down from the seat, however. I recently needed to grind two stumps (1 15" oak, 1 6" pine). In order to borrow my friends stump grinder, I would have to borrow his tractor as well, becouse his stump grinder needs two rear remotes to operate, and my tractor only has one. With the price of fuel to drive two hours to get his tractor, drive two hours home, grind two stumps, fill his tractor with fuel (the least you can do when borrowing), drive two hours back to his house, and two hours back home, I figured it would be easier to rent a standard stump grinder.
Half day rental was less then $150, and I managed to get probably 20 stumps ground down. Most were 6" pine, but there were two 15" oak and two 15" pine.
My advice, if you can, take out the offending trees, work around the stumps, and rent a stump grinder to finish them off.