All good suggestions. My LBS spent 20+ minutes checking out my derailleur, even went took my bike out for a test to hear the noise themselves. Their diagnosis? "Break in" issues -- the teeth on the chainrings need some more miles to smooth themselves out.

I will double and triple check the B screw. And I'm certain it's not the seatpost or pedals.

Anybody running DA 7900 who cares to comment on their experiences with drive chain issues?

Thanks!