Someone posted about this just this morning. They reported that about 80% of the people at the signature restautants were in business casual clothing and 20% were in theme park clothing. No one was asked to leave for wearing a mickey t-shirt, but they are hoping that people will dress nicer in accordance with their written but unenforced policy. The decision is yours. I would be uncomfortable being the underdressed one in the room, but that's just me.