I have had my personal diesel (Duramax) since 2009 when it was a company truck for me....disliked the old diesels, bit took less than a month to know I would be keeping this one. The factory performance is more than I could ask for, but would never do the upgrades so many do. That is usually when issues show up.
I like performance, this truck gives it for a 8,000+ pound beast. I would never go back to a 6.0 gas, it is just to bland....
Sane with the 1500's. The 5.3 gets you there and back, but to me it is a bit of a slug. Tease yourself sometime and take a 6.2 for a drive. Totally different truck and a pleasure to drive!