Sorry it took so long to get back to you. Yes, I had it done at a place here called Les Schwab. I needed new wheels since there was a problem with backspacing on the original wheels. I kept my tires, but put on some 285.75R 17 Toyo's.
The width is about 2 1/2 inches wider on each side, so the mud flaps that came stock do 1/2 the job they used to. Since it is higher, I do like the wider wheel base. It feels as stable as if did before and it definately did nothing to the smooth ride. The extra clearance has saved me some repairs already. If you get the lift, keep in mind you may need to fabricate new mounts for your skid plate on the front differential. Good luck, it really makes a big difference, and other avalanche owners feel inadaequate!