Interesting concept. I would try it. We could take our daughter - she took ASL for her foreign language requirement when she was in college. At the time she was working for Johnny Rockets. The first time a deaf customer walked in, the server didn't know what to do! Loverly was the grill cook and noticed some confusion just across the counter at a table. When she found out her superpower was needed, she came to the rescue! Needless to say, she felt really good she was able to help.
Like taxy said, I would think the success of "Signs" depends on the quality and value of the food. I hope it works out for them and their is some expansion of this concept.
"Cooking is the art of adjustment". ~~~Jacques Pépin