If disc brakes were desired on a drop bar tourer are cable disc brakes like the Avid BBV not compatible with drop bar levers, whether standard or V brake levers like the Tektro RL20 or Dia Compe 287V?

That said properly I've always found properly adjusted V brakes strong enough. Cantis are a bit harder to adjust as there is more variables.

http://sheldonbrown.com/cantilever-g...tml#mechanical

But as to the main question are production touring bikes any good? I'd say up to a point yes. The gearing is often a bit high and the wheels not good enough. Other than that they are catering for the majority. If you have niche needs you need to customise an off the shelf bike or build your own.

As for the disc brakes, belt drive, Rolhoff hub, big tyre clearance - definitely a niche market.

http://www.shandcycles.com/2010/08/15/mor-dearg/