I had the same question, so I asked here...
http://elcova.com/groupee/forums/a/t...1/m/3801072621
Check it out.
In my opinion GO GET THE H2, I love it, and as was mentioned before by other member, I also have other "fun" vehicles, a BMW 530i, a brand new 2006 BMW 330i (E90) new model, sport suspension, premium package, the whole 9 yards, and somehow since I got my H2, the H2 seems to be the only car being driven.
Regarding gas, I don't know if it is an illusion, but the 530s' seem to eat as much gas, since I remember going to the gas station a lot, and only able to put "premium" in those cars...
Just get the Hummer, you won't regret it...