I didn't get the GXP for a few reasons.
1) I didn't want to pay for it. Not that I couldn't, but didn't want to. I had a hard enough time with my own mind to part way with that much money even though my wife pretty much told me I could get whatever I wanted
2) The GXP gets 20mpg vs 24 with the GT. I'm already taking a big hit going from my Jetta TDI (50mpg).
3) Really I just don't need it. My truck is going to be my "fun" vehicle and the G8 is my commuter.