I've never driven a GT3.1 or .2 but owned a 997.1S and have driven a 997.2S and the throttle response in my M3 is better (with M power button engaged).
I have to believe that any versioned 997 GT3 would be at least marginally better than the M in the throttle response dept. No? The car is purpose built for the track.
A bit OT ---- Went on a run today with plenty of powerful cars (Gallardo, 997 Turbos, a ton of 996 TT's, an E46 M3, a 993, Z06, four Lotus's, a PanameraS) and I was simply amazed how well my DCT M3 fared. It always seemed to be in the right power band coming out of turns, etc. The sound was simply awesome. In the short period of time (30 days) that I've owned this car, I have determined that I may hold onto this one for a while.