Opinion needed...I need payload but never tow... upgrade to a 2500 with a 6.0 or no??

Bought a 2004 Silverado 1500 4x4 Z71 ext cab with a 5.3 vortec and 3.73 gears 5 years ago. Have driven it loaded down across country 5 times and done LOTS of mountain driving! Its hauled 1500+lbs of camping and fishing stuff, kayaks, mountain bikes, heavy coolers, plus people and a big dog, through the Canadian Rockies, Sierra Nevadas, and about everywhere you can go in the backcountry. I never tow, but need plenty of payload. I drive some long heinous shuttles on STEEP, ROUGH dirt roads with big loads, sometimes with 6 or more people and kayaks, and loaded rafts too. The Silverado has been great, but did need some big repairs. The transfer case wore out at 60k miles when the encoder motor kept ghost shifting. And the tranny went out at 110k...burned up the 3-4 clutches. Replaced a water pump too. But overall, not bad for a truck that was truly used for real stuff that a 1/2 ton truck should be able to handle... in my opinion. Way better than those Tacomas and mini-vans that my friends use :no:. Anyhow- it does ok on gas too...16-17 loaded. Now at 126k miles, I'm shopping for my next baby.

I remember the 'heavy half ton' of yesteryear and wish I could get that. Or a 3/4 ton that isn't a HD. I'm looking at a 2010 Sierra 2500HD with the 6.0 vortec and 3.73. I know I don't want the 410 gear if I want better mileage, correct? And even though they're great, I can't see myself needing the diesel/allison combo either. Does anyone think its still too much truck? I'm just thinking since things broke on the 1500 I might need to go beefier. Thoughts on the vortec 6.0 or std 6spd tranny anyone?? I want my next truck to last a little better.

-K (lady in Red Silverado)