HC,
Did you order the factory brake controller??? If not, add it if it's not to late!!! We have a '13 with the itbc and it is amazing!!! Though my only comparison is do a Draw Tite Activator time based model (I think thats what model it was!).
I had a '10 with the 5.3/6spd/3.42 and it pulled ~7500lbs without an issue here in MI! If needed, drop a gear (or 2) on a hill, and let the motor rev-!!! Only reason we have a 2500HD now is as mentioned, we were short on payload with a family of 4 (growing 10yo boys), added options on truck (truck cap, spray-in bed liner..etc), bed cargo, and tongue weight.
Congrats on the rig!!!!
Dspencer, You can get the 3.73's now with the 5.3 in the new '14's! I think the combo is available to order now??? I thought that combo would be pretty sweet, and can only imagine what the 6.2 combo is like!!!
Chris