Power is very smooth (almost like a gas motor), but I think the new Duramax's are the same way. I can barely feel lag (except when towing a lot) in the turbos. Our truck is a base 550 with a 16 foot bed and drives better and smoother than most half tons. Its very enjoyable to drive. I was looking at about the same #'s on my cummins (5.9 w/ tune) as the 6.4 is stock and it was a completely different feel. Both the Powerstroke and Duramax are quiet as a Prius. On the DPF note I know when we first got the truck new I ran red fuel in it because I could and I thought it was a bunch of "EPA" propaganda, but later I noticed the truck starting to miss and loose its responsivety. I also noticed that it slowly leaked coolant so we took it in and they fixed it all under warranty. In the manuel it says it will throw a code if you run offroad in it, then to fix the code you have to cycle 3 tanks of ULSD through it and the truck will delete the code on its own... It never did that. Other then that I love it, its ran very hard every day, more than enough power than you really need (I almost wish I could detune it so the guys don't drive it as hard), great work truck. Test drive them both.