Rod, I recently traded an '07 1/2 ton pickup for an '08 3/4 ton Diesel because I didn't like the way the smaller truck pulled our '01 25' trailer (6500 lbs loaded), and the 1/2 ton had the 4.10 gears. It to was slow as molasses going up the hills, especially at high altitude.
By the way, if the 1/2 ton you are speaking of really has the 4.10 gears, and not the 3.73's, someone changed them...they are not original as GM does not make 4.10 gears for the small 10 bolt rear end.
Anyway, I am much happier with the 3/4 ton Diesel, but the draw back is it is expensive. Expensive to buy, expensive to maintain, and the newer ones ('07 1/2 on) DO NOT get the fuel mileage of the older Diesels. Figure 14-16 MPG arond town, and 16-18 empty on the road with the '08 Diesels. But hey, at least the fuel is more expensive.
Edit: Just noticed you are in BC, Canada, and your laws and emission controls on Diesels up there may be different than here in the States. The real problem with the newer Diesels here is the diesel particulate filter in the exhaust system, and resulting required regeneration cycle the the truck must go thru. Causes reduced power and increased fuel consumption.