The GT is my daily driver, still as fun to drive as it was the day I brought it home. Actually a bit more with a few mods. A TCM tune makes the auto a whole different vehicle and by far one of the biggest seat of the pants noticeable changes. If the option for a manual in the GT was there I probably would of went that route, but now living with the auto (especially post-tune) I really have no complaints at all. The auto was actually quicker in straight line in everything I've seen, and from experiences of gxp auto/manual owners, since you get perfect shifts every time. It'll kick the rear out a bit on the 1-2 shift, and give a nice bark on the 2-3 shift which is at about 70mph. Unfortunately I haven't gotten it to the track yet.
Better hurry if your looking for a new manual GXP, as what's in the states now is what's left for the G8 - either on dealer lots, or a few at cali port going to dealer lots. There were only about 1900 GXP's made and I think only around 30% of them were manuals.