For what it's worth, I have a Sony Tap 20 unit in my office, which we're planning to turn into an electronic voting prototype, donated by Sony and Microsoft who are intrigued by the idea.

You can think of it as a big, heavy, battery-powered tablet. Or, you can think of it as an all-in-one Windows 8 touch-enabled PC that happens to have an internal 2.5 hour battery and ships with Bluetooth keyboard and mouse.

If what you want is to have sheet music in front of your face and have swipe gestures to go between pages, this Sony thing plus a swipe-grokking PDF viewer might be exactly what you're looking for. You will need something more substantial than a standard music stand to hold it, though.