I plan on keeping things till they fall apart... Right now we have 2-'04 Chevy 1 ton duallies, 1 w/duramax and the other w/8.1 gas. We got them a year apart with the gas being a off the lot new purchase. Both of them are 150k+ the gas is starting to get a few nickel and dime problems and I don't plan on getting rid of it as both trucks have a 7.5x9.5 aluminum bed and goose neck mounts. They are solid from a body standpoint, but again, 150k on a gas engine is starting to show some wear.
Maintenance costs are something I would definitely like to know comparing a 1 ton dually to a medium duty truck like a NPR... such as routine maintenance parts. We currently handle everything as much in house as possible (fluids, brakes, tie rods, ball joints, etc...) and could probably do the same on a NPR, but is the cost relative as comparing 1/2 ton truck parts to 1 ton vs. 1 ton to medium duty parts?
Also, being able to drop carrying a trailer and the additional wear/tear that goes along with a 16' landscape tandem w/dual brakes.... although it's very cheap maintenance compared to a vehicle...