$6k, that's a lot, but it puts a larger suspension, engine, axle, etc. A good thing.
Problem I see tho, still ... the 1500 comes with a Double Cab (previously X-cab, but with different door hinging) ... at this point 2500HD does not, although I've been told it will eventually -- and the Crew Cab is another huge bump ... and one I'd never make. SO, add the CC to that $6000 and you get a pretty large $$$ difference between 1500 and 2500HD at that model.
When you start talking CC and 4x4 on a 2500HD, and compare to the 1500, it's a pretty large difference for what you actually get in 'upgrades'...
So, now you're talking $10k, not $6k ... Seems a pretty big jump for 18" more cab (from single cab) and axle, and bored out block etc. It's not like it's a totally different truck, the basics are the same - Same body, same seats, same windshield, same tailgate, same bed, same AC, same Electronics, same steering, -- could go on, but you get the drift.
Yes, I get it ... payload and brakes etc. But, the difference in price is much more than it appears at first glance. Based on the differences I see tho, I'd never go with a 1500, now that I get a good look at the 1500, it might have the engine power, but there's a lot more to hauling a TC than the engine ... But, it's a big $$$ hit to make that jump.
Guess we pay for our toys ... TC makes this happen, and that 1500 probably be plenty for average TT towing, even small 5'er. But hauling a TC, takes a little more meat under it.