Sounds interesting. But with those things you never know how many live songs of which bands actually make it onto this Wristband thingy. I highly doubt it will be a lot of full shows, I guess something like a complication of a couple of live songs of the bands.
They had the same thing for Rock am Ring/Rock im Park this year, not only it was totally overpriced (for a USB stick) like Sonisphere, the live music you could buy afterwards was more than a huge let down. I haven't even heard of 95% of the available bands, and the best of compilation contained like 1 of the bigger bands.
Back to Sonisphere, like always bands/labels have the last word on those things. So either we end up with nothing, a few sings or maybe even the full show.
But if like the idea of those things, the demand for live material from attended shows is getting bigger and bigger.