I was on the phone today with Co-Motion discussing a future strip & repaint of our bike. As an afterthought, I inquired about a braze-on for a rear disc brake. I was informed that a braze-on isn't an option (owing to the thickness of the chainstay wall), but that the rear triangle -- seat tube, chain- and seat stays -- could be swapped out (along w/ a new cable routing for the disc). Price: $600 (plus the disc and brake hardware)(rear hub isn't really a factor as I'll be going to a new wheelset anyway [I'd be specifying a disc hub instead of one threaded for a drum]). Is the added braking capacity cost-effective?