Oh, I agree with you on the ability to tow!
And the stopping ability with surge brakes--gotta have it!!!-- . My point is the strain on the drive train, (mostly engine) Engine winding out, and (tow/haul/On) staying/maintining higher rpm and Lower gear. The Gross Combined, or Power to weight Ratio is taxing on the 6.0 liter, She's Hav'n To Work!, IMHO. I to bought it to use, and do so. But, compairing it to Our 02 silverado, 8.1 w/Allison, for towing--It's not even in the same class!--My prior Rigs (tow/work) were All duallys, 98 GMC 6.5 detroit, 01 Dodge Cummins 24v, And 01 GMC Duramax.
Terminator, hit the nail head, MPG Towing. The H2 wasn't (this year anyway) designed to do Heavy Towing. Although it does tow well, It works Hard Doing It! Again, IMHO
