I haven't had it a year but I have had it for the last 20k miles. I do love the way it brakes and downshifts. I have driven a dodge with a jake brake and the jake brake does work better than the tuning I have but the cost isn't worth it to me. I paid $400.00 for the SCT and I get unlimited tuning so everytime I change something on the truck I get a new tune.
As long as your engine is not the LMM we have an exhaust brake that will work just fine. Due to the new DPF system we have not had a chance to come out with a brake that will work with all of the electronics.
Pacbrake has the exhaust brake kits for all of the Duramax engine except the new 07/08 LMM with the Diesel Particulate Filter