Well, now you've started it.
Conventional wisdom is that diesels are simply safer. Diesel fuel is not volatile. You virtually can't light it with a flame, while gasoline vapors are quite flammable.
I'm not sure I would get too anxious over fuel economy, but getting 10,000 hours out of a properly maintained diesel is not uncommon. I can't quote gas engine durability, but it's a fraction of that.