There is a difference between dutting/counting and using a metronome. A metronome we know is never wrong in terms of where time is whereas dutting and counting is not always correct. There is a better chance of someone rushing/slowing down by following duts, counting, watching feet, etc. than with a metronome. It just doesn't seem like it SHOULD be allowed. Obviously it is, but I just think it's an easy way out. I mean the ensemble is fantastic clearly, but I think using a metronome during a performance at any time is an "unorthodox" method of keeping time.