Sounds like you have quite a bit of experience with disc brakes, including how to maintain them. That should go a long way in your decision. If it were me, I'd use them in a heartbeat.
Curious about the frame choices - why did the LBS recommend Salsa and Kona over Surly?
I don't understand your the sentence toward the end, just about "Discus...." I think you're making a comparison, but I can't tell what you mean.