The iPad is working well in rehearsal! I brought all of my paper music with me for 3 rehearsals in a row, but have stopped doing that. The first rehearsal I discovered that for one piece, I only had the even numbered pages, but that was easily fixed.
Annotating the music in real time takes some practice. In order to get accurate markings, I usually zoom way in on the score. I haven’t found that a stylus is any more accurate than my finger.
So far I’ve remembered to put the tablet on charge the day of rehearsal, and battery life has not been an issue.