Ok. The only reason I asked is because when I went to project options to send the built in audio metronome to a buss, Sonar was providing me a buss called "metronome" and I didn't set one up like that, so it almost seemed, at first glance, like it might be some kind of built in hidden buss. i didn't investigate further.
Anyway, I love your approach over all. Sample accurate metronome I think is absolutely key, and being able to setup some metronomes that swing, etc...could be beneficial as well. All that can also be done by using a midi track sent to Session Drummer2, but then you have to deal with paranoia about the timing of the midi track. Just make it with audio and then it will be sample locked. I like it.