Have you driven a post 2007 emissions equipped machine? My type of city driving (3 miles to take the kids to school and 3 miles back home - I work from home) is horrible for the DPF-equipped trucks.
Yes, my diesel gets worse city mileage than the gasser I had before it. Granted, I'm comparing an F250 diesel to an F150 gasser, but still, I'm reasonably sure I could get just as well with a V10 truck as I do with my 6.4L diesel in city numbers.
If my diesel didn't tow so dam well and put a smile on my face when I hook my fifth wheel to it, I'd trade it for a gasser in a heartbeat. Thankfully, I only drive 7500+/- miles a year, so fuel costs aren't that big of a deal to me.