Just installed the revised tune. I have been running the 600 QR. Didn't get to put very many miles on but was able to go through the relearn process for the transmission. So far I am VERY impressed with the power and shifting. A little afraid to get to crazy with it until I get some traction...
So far I really like the 600 QR tune. Think I'm going to stick with that and I'm actually getting better mpg's with the 600 tune than I was with the 550 as long as I keep my foot out of it.