If we up the ages, I'm actually of the opinion that we up the Academy Graduation age. They will definitely be stronger though than their twelve year old selves. Hmm...I'm fine with upping their general skill level to canon high genin to low chuunin levels, but they wouldn't have any true combat experience. Also, I'm a little iffy on Neji and Hinata being fine. Without Naruto to knock sense into him, I don't see it happening that much.