So, i just came up with a cool idea.
It won''t help you with already recorded shows, but it may work for shows you tape in the future. Though it may not be too hard for some to time stretch a audio source to line up a matrix recording, if you could do it much easier, wouldn't you?
Okay, here is my theory. You just finished recording a concert, and about to pick up your equipment. You pull your recorder out of the soundboard DON'T STOP RECORDING! take the line out of the recorder that is taping with your microphones, plug it into the line in of the recorder that was taping through the board. Both recorders are still recording. Now just clap in front of your mics, then you can stop recording on both recorders.
Now, you have a really obviously sharp peak at the very very end of the recording. All you have to do is line up the show at the beginning, and then time stretch at the end so the clap lines up perfectly.
How about that? Think it will work?
-josh