I didn't really see it talked about much, so I'll state the obvious. Once a load is moving, the easy part is done.... The hard part is the actual stopping, especially in an emergency scenario. SOOOO many guys are under trucked nowadays for the loads they are hauling its wildly unsafe for everyone involved. I know the increase expense between from the 1/2 to 3/4T especially if you add in the diesel, but the 3/4 gives you so many more options in the long run, you'll probably never wonder if your truck can handle the load, you'll just hook and go...
Your back may tell you otherwise though!