I have two college music majors. I always take my knitting to performances, but usually I knit while waiting for it to start, rather than during the performance. I can think of 2-3 performances that I've knit through...and in all cases, the lights were low, the auditorium was not crowded, and I was in back sort of "alone."
I figure it's distracting to others, even if it's quiet. Just the constant movement would likely be distracting, I think.
I also knit in restaurants while waiting for my food, or after I'm finished while waiting for dh to finish or waiting for the check. But only when I go out with dh...he understands, it doesn't bother him, and he knows I'm listening!
I'm Knittermom9 on Ravelry