Upload & Sell: On
You can go round and round with all the possibilities but, as always, follow the money. The dance studio has two reasons for limiting photography to their own shooter. The first is that they want to rule out a million different flashes and phones and iPads disturbing the performance, the second (and the order may well be reversed) is that they hold all the cards and you have to buy their stuff, or not.
Most attendees aren't you Dan, they are folks who don't care about destroying the performance for everyone else, so they will be crawling to the stage, standing up, flashing whatever. You, me and the rest of us here could be there, shoot a zillion images and they wouldn't even know we're there, but that's not true of the general public.
Here's my approach, and it's worked since forever. Get to know someone that can pull strings, build a relationship of sorts, whatever it takes. In most cases it can be done. Heck, you can probably outshoot their "pro". The subtle approach generally works, find out who is pulling the strings and see what can be done.