However, it would not be the end of the world if you brought your headphones. I was able to test some woo audio amps with my own HD600s that they themselves did not have on display. So if you are planning on upgrading your gear anytime soon, I would say that it would not be a bad idea to bring headphones. However, be prepared to leave them in the car.
Also, bring CDs and Vinyl. A lot of rooms will let you play your own music to test their stuff.
Good point! I totally forgot about that. I think I'll take in my headphones today and listen to some of the Woo and Stereodesk setups.