I made my own rearsets for my Derbi. 1" back and 1.5" up. It seems a little too high at first, but then after a while you get used to it and you can still drag your toe even with 1.5" up. I made my own shift linkage so the lever will still be in the proper place.
It uses the hole on the stock rearset for the lever pivot point, and while I was at it I switched to reverse shifting which helps a shitload on Stockton, especially out of the left in front of the pits. You can keep your full lean angle and still shift, instead of having to stand it up a little to get your toe under the lever.
Bob's rearsets are definately durable. I've personally seen three or four crashes on them and they never even bend. The only thing I don't like is the height. They are only about 1/4" to 1/2" above stock and I wore the crap out of my toe sliders in just 2 races on Bob's bike. Bob's rearsets with those little rearset spacers and some custom linkage would be the prime setup.