Multicam question

Soon I will be on a multicam shoot where we are filming a live band. Going to be recording audio straight from there mixer output and also an external source for crowd noise etc, all fine.
I believe the band are going to be playing to a click track so there tempo should be the same and if they are good musicians there songs should pretty much sound the same. Question is we are going to film the rehearsals just as a backup and for additional angles.My question is that if I sync all the footage from the main performance together then could I in theory sync the rehearsals takes to the performance music. Should FCPX do this or will it realise that the music is different and from different takes?
Thaoughts?

You can make FCP treat them as different angles. You might have to tweak sync, but multiple takes if recorded to playback with the cameras recording audio for sync should sync pretty easily. FCP sync seems pretty good at this.

Thats what I was thinking or when the master sync is complete then manually sync other clips one by one using the normal sync function.

No real reason to do that if they're always playing back to the same track. It might help if you assign separate angles for each pass, then tell FCP to assembly using angles and not camera name or content created.

The scary news is that having done a lot of live concerts, I'll warn you, even if playing to a sync track on stage, a lot won't match up, so you'll be doing a lot of manual tweaking.

The really great news is that FCP X's multicam system will let you do those tweaks super easy.

I'd strongly recommend doing Ripple Training's multicam video course first, and REALLY learn how deep and powerful multicam is before doing such a complex project. I'm confident it will save you a lot of time "learning as you go" on such a big project. That is if you haven't done it already. I picked up so much from it that isn't in the user manual, it's saved me a lot of headaches up front.

Yeah so if I use sync by angles then even though the audio will be the same, by using one master sync track, then the different angles will be assigned to different tracks.

Ben I have done that already thats what sparked the original question because I've been thinking about how to do it. Even If I do get the main performance right first then add to it. I do feel confident after watching the RT tuts on it.

I have shot multiple takes on a live edit, and BenB is right, a lot is just out. But overall you will get away with a few angles that will work well.