I concur with everything stated above. I love my dually and wouldn't go back.
I also have more than one vehicle though, so the mileage isn't really an issue.
Like many here, I also felt I wanted more truck than I needed, just so if the need did arise, I'd have the vehicle to handle the job.
I find the only draw back to be that the dual rear wheels go through tires faster than the front tires........nobody has been able to explain to me why though.