I can and did justify a diesel over gas!
I agree with your findings. My fuel milage is a little better at 20-21mpg on the open road and 14-15 loaded heavy around town.
I'll add a few more opinions.
I bought a 06 Dodge Mega Cab with the 5.9 Cummins. Motor has been trouble free for 192,000 miles so far. I expect it will run close to double that and my cost per mile to own gets lower every mile.
It's been pd for for several years and I sure don't miss payments.
I bought the diesel mega cab because of the room & I can leave it running in 100 degree weather and the AC still blows cold. Cruise can be set, when parked, so that the engine rpm is run up to a fast idle just like the big rigs. I'm a Realtor and it pays to keep my clients cool when out looking at homes.
If you can stand to drive the same vehicle for 3-400,000 miles, I think a diesel is a lot cheaper to own than gas.
My previous experience with gas trucks is somewhere around 150k they are junk. I've never gotten a rebuilt motor the was worth it. I think it has to do with our heat down here in Houston.