This idea seems pretty solid to both ensure that servers are properly compensated during slow shifts but also see an increased compensation for busier shifts.
Personally, I strongly dislike tipping in the sense that at a restaurant I want to pay what I owe. I'm not looking to weigh in on whether or not my server did a good job or not - that's a manager's job. If my server is that awful, I'll report the server to the manager and let the issue be settled as I would when shopping retail. But beyond that - I feel that those who tip well - all they're really doing is compensating for those who don't. They're not so much rewarding a server for a job well done, but letting poor tippers off the hook.