I've added a pair of HD Hero 2s to my kit to get drummers. I've been experimenting with placement.

Here's on the crash cymbal. Shakes a bit, but the effect is actually pretty cool:

The Who - Love Reign O'er Me - Evanston School of Rock - YouTube

It's useful in what I shoot. In this case, the drummer is half the height of the lead singer and barely as tall as his high-hat:

Television - See No Evil - Evanston School of Rock - YouTube

I've done several concerts since the original post. Here's the Chicago School of Rock's tribute to Progressive Rock doing Roundabout by Yes. I had the two GoPros on the drums and covering both keyboard players:

Yes - Roundabout - Chicago School of Rock - YouTube