The 6.0 is really the weakest of the gasser options out there, while it may get the job done I'd give the Ram 6.4 or Ford 6.2 a serious look for better performance. Othet than the gas engine itself, the 2500/3500 SRW gm truck is a great platform.
I tow 10k with a Diesel and until they offer the 3.5 Ecoboost in the Super Duty I won't switch to a gasser, the low end torque just isn't there and makes for much more of a strained towing experience.