I pulled one of those motors out of a wrecked suburban and put it in my GMC crewcab dually, and my best friend has an '04 Chevy 2500 pickup with the 8.1.
It does pull well, but it destroys fuel!
I did do what you mentioned, got a Dodge with the 5.9 Cummins and it's LIGHT YEARS better at towing and mpg.
About the Dodge/Cummins trucks: there's a LOT to read up and learn about them (or any of the other brands) before choosing what model years you want to own.
The earlier 24-valves (1998.5-2002) are a whole lot cheaper to fix. The later 2003+ "Common Rail" Cummins are also excellent but things like injectors are pricey.
All have well known and documented shortcomings that have been figured out and have their solutions, and they all cost money. All can be made to work great. You need to read on Dodge Cummins truck forums thoroughly before going out and blindly choosing one.
I can tell you my almost-20-year-old Dodge, after the right things were done to it, will pull every bit as well as a new one for less than half the price and the 8.1 Chevy - which I also own - is no comparison. But it still cost a whole lot more to get it there than a gas Chevy.
