We have a huge Cinco de Mayo event coming up shortly and we want to use 2-3 cameras. We have an EX1 and I am trying to decide between the EX1-R, EX3 and possibly, the PMW 350. At the moment, lensrentals.com is by far the least expensive for the EX1-R and EX3 so I would need some convincing on the 350.

Besides the obvious accessories (extra SxS cards, batteries, tripods), what else would/should we rent?

We will start shooting in the middle of the event, so what is the best way to sync the cameras together? What option is there to use the EX3's genlock via wireless?

Thanks

I wouldn't worry about sync for that kind of shooting. Unless this is a very unusually boring Cinco de Mayo event, there should be little question about which video goes with which. If two (or three) cameras are shooting the same thing, it should be easy to sync the clips using the sound tracks. And if you have a clip from some other place, you can treat it as "wild" B-roll.

Well, I plan on recording wireless from the stage mixer using the Sony plug-on transmitter, and then possibly using my NTG 3 and NTG 2 for crowd and ambient sound. However, I am worried that I will have phase issues.

Phase issues is a completely different matter and has little to do with sync. Where do you expect to have phase issues? Nothing about your descriptions suggested that audio phase might be a problem.

Recording straight from the stage mixer and then being 50 ft or so away and recording using shotgun mic's on the camera. The shotguns will be xx milliseconds behind the audio from the stage mixer. However, I should be able to fix it in post now that I think about it.

I keep on meaning to try this for multi-camera shoots:

Singular Software (http://www.singularsoftware.com/pluraleyes.html)

Looks like it could save lots of time.