The data tells me it'll be a decent improvement, but data don't always tell the whole story. What I never liked about my 5.3/6speed was mainly the transmission. On long hills (or should i say slight upgrades), it would shift (in tow mode) from 6th (2,300 rpm) straight to 4th gear (3,800 rpm) skipping 5th altogether. AND, a GM V-8 just don't sound happy to me at 3,800 rpm. This was a Silverado w/ max towing pkg and 3.42 gearing.
BTW, I'm pulling a 32ft Outback 280KRS at about 8,000 lbs. I hope this new combo (and 460 ft/lb torque) will ease on down the road - or up the hills - a bit easier.