The 6.0L is the same engien family/design as your 5.3L. It's larger displacement means about 13% more power. The 6-spd trans have very similar gear ratios. But 4.10 provides about 20% more wheel torque and get the engine over 3000rpm quicker where the power is. Do you think you'd notice 35% more power?
You are probably at 8000 pounds loaded with 1100 pounds of TW. Your payload is in the 1500 pound range. The 2500HD gasser has almost double that payload.
So compared to what you have now, you'll feel more comfortable towing. Hold 5th gear longer, get up to speed up and hills quicker. And handling will be better.
You may want to hold out to see what the 2015HD models offer. I am hoping for significant power improvements. You may also want to consider a SRW 3500 if you want to tow a 5er. The upcharge is less than $500 over 2500 with about 1400 pounds more payload. 3000 pounds is not much payload for a 10-12k 5er. Take off 200 for hitch, people, and stuff in the bed.
