Although there was some doubt at first, our server called the manager and worked hard to take care of our party's gluten-free, vegan, gluten-free and vegetarian, and gluten-free and vegan needs, while being extremely polite about it. I even heard him assuring a chef, who was concerned about the order of black mushroom sushi (not gluten-free), that it was for someone without that need; he also thanked the chef for his vigilance. We started the visit expecting some people to have one choice and be thankful for it, but we ended it with everyone full of delicious items that they took the initiative to modify. One child was so happy, she was insistent on tipping the server with her own money.
Just make sure you are not tight on time, but if you have the time, I assure you it is worth it.