I have a 3/4 ton Duramax LBZ crew cab. The main reason I bought it was to tow my 30' enclosed snowmobile trailer out to Wyoming to snowmobile. We drive straight through so the truck is running for like 18-20 hours straight. I just thought a diesel is better suited for that kind of towing. Will a gasser do it. Yep. Will a 1/2 ton do it. Yep and I have done it with a 1/2 ton.
With that said If I was buying a truck just to drive back and forth to work and an occassional trip towing to the U.P. I would get a 1/2 ton gasser for economic reasons. I can buy gas cheaper than I can diesel. Our 09 1/2 ton suburban gets 21 MPG on highway trips and 16 or better in town. IN the long run cheaper to drive a 1/2 fuel wise and they cost less.
I love my duramax but I new 1/2 ton gasser is a nice ride as well.