Well, I picked them up half an hour ago, and I'm satisfied... I don't expect the Rebel G will be seeing all that much use. I'll probably sell it off, along with my old 28-90mm. Between the two, I should be able to pretty much offset the cost.
I think I'll like the 28-105mm quite a lot better. It has the metal mount, USM, and full-time manual focus. It's a touch faster, for what that's worth. It definately FEELS a lot better on my camera, and (again FWIW) looks better.
I'm pretty happy... Now I think I'll play with my new toy for a while. 