I love my diesel (F-250 PowerStroke) and towing with it has been great. The torque curve is amazing for towing; after all it's what diesels are made to do. Your maintenance costs will be higher - Figure around $100 for an oil change because diesels use around 15 quarts - but the longevity you can get out of a diesel makes it worth it to me in the long run. Duramax engines are very stout and Allison Transmissions are well built also. I traded in a 1988 F-250 with the 460ci gas engine for my diesel. Would I do it again? You betcha.
Biggest problem with a diesel? It won't be long before you start hearing about things like Banks, MBRP, Bully Dog . . . .ZOOM!