I have both the 6P and the G2 (in yellow). To be honest, if I had decided to get the G2 first, I would probably not bothered with the 6P!
I really like the Nitrolon, it feels better to hold, and as others have commented, it doesn't wear nearly as badly as the type II coating on the 6P, which I'm forever worried about scratching!
The G2 is also lighter.
I'm not sure about running the p61 in the G2 though, it's lens might melt, others may know more, but for me that's not an issue anyway as I only run the p60.