If you know you will be doing suspension and wheel upgrades regardless of size of truck chosen, go with the 3/4t. If the 1t SRW will give you sufficient capacity without modifications, it is less expensive to go with that model. In my model year the GVWR could be between 9,600-11,500 lbs even thought the running gear and frame is the same - The only thing that changes is the standard equipment (also available as options on the lower rated trucks) and the model number. Interestingly, you can see identically configured trucks getting different GVWR's so that payload stays at a similar level whether you choose a standard cab or crew cab...
GM limits which body styles and wheelbases are available in 1t verses 3/4t, so that may also be a reason to choose the 3/4t and make your desired upgrades. I know my 142" wheelbase Ford sure turns sharper than these guys with 30" longer ones. My overall length with truck camper is the same as owning a crew cab long bed truck without camper but with a much smaller turning radius.
