Chris - Yes, you should bring your own theremin if at all posssible.
Here's some info sent the other day by Rita at the Orange Peel.
"In just a very short time we will be gathering at the Orange Peel for quite an event! I wanted to remind all of you of the registration time on Thursday, where check-in to the event will be taking place. We look forward to hosting all of you and even more to what the days of the festival will hold. Should you be a one day participant, we can check you in at The Orange Peel on the day you choose to come.
Some of you have asked about bringing your instrument. It is a personal preference, and if you are able, by all means – bring it! If you cannot, Moog will set up some theremins around the venue for the duration of the event."
Jeff