The diesel/gas debate is interesting. I've had a 92 Ford with the old 7.3 naturally aspirated diesel. It got about 16 mpg in the city. I currently have a 2000 GMC Sierra 2500 with the 6.0L gas engine. It gets about 11-13 mpg in the city. The 7.3 was a great engine but when it broke down, maintenance costs were really insane. In contrast, the 6.0L gas has been bullet proof and has had next no issues with it apart from the fact that it sucks up gas. Even basic things like an oil change where much more expensive on the diesel.
Overall, the choice of diesel engine depends on what you're doing. If you're pulling heavy weight or hauling heavy loads or driving for long distances most of the time, the diesel is great. But, if all you're doing is carrying equipment or loads to a job site and then the truck sits there before moving on to the next job, I'd take a gas truck instead. It has a lower initial cost, lower maintenance costs, etc. Don't forget as well, whether or have gas or diesel, the truck will eventually fall apart around the engine. So, the diesel might last until 400 000 miles but what happens if the truck starts falling apart around 250 000 to 300 000 miles?