It depends on a lot of variables. If you're expecting gen lock, go on the AF100/101 route. But if you don't need, the GH2 touch-AF is able to do the work ;-)
Even though, I'd use the best fast (manual) glass my money might afford. As well, several units and good editing, yes.
All that I have been reading is saying between the 14-140 lens and the new improved auto focus function in the camera, we should be in great shape doing live IF we have sufficient light. The 14-140 lens is the one that has been optimized for video and auto focus, but it starts at 4.0. We have increased ISO, but I'm afraid dumping a bunch of gain is going to bring out noise.
Live shooters have been starting at 2.8 for many years. It requires high sensitivity and a lot of times some pushing post, but it generally works fine for everything except audience shots. Yes, the GH2 can work for live events. It will work exactly as well as the GH1, which I have used for this successfully. It is not, however, the ideal camera. It's a camera that works fine if you have it, but should certainly not be your first choice, especially if you don't have extensive coverage with other cameras.
In good lighting, your far better off using the TM700 for live event shooting but what I will say is that the auto focusing of the 14-140 isn't bad at all when it comes to live event shooting.
Every one of these videos were completely hand held and I suspect the GH2 to do at least a little better. http://vimeo.com/16785241 http://vimeo.com/6256427 http://vimeo.com/6492716 http://vimeo.com/11655795
I have a whole lot more examples (maybe even better) but I don't think I need to post any more.
For daylight outdoor event, I'm getting 14-140. But for indoor event, it might not be bright enough. Fast dslr 2.8 zooms such as tamron 17-50 might work at ISO 1600, but they are not parfocal. Some TV lenses are fast and parfocal although they require ETC 2.6x. I ordered Canon B4 to Nikon adapter for that. Hopefully Canon ENG B4 f1.8 lens can handle indoor event under ISO 800. Definitely no prime lens for live event... No time to switch primes.