I had Avid discs on a Giant OCR Touring (BBDB, predecessor to the BB7). Anyway, I didn't like the Road implementation of the Avid cable brake. Mushy feel and too much lever travel. I'm not the only one. Hydro discs are still preferred for MTB; I think they are an improvement.

I have seen a similar kludge for cable/hydro integration. It used hydraulic brakes mounted on the bar tops (like "cross" levers") drilled so that the STI brake levers cable pulled on the hydraulic levers and caused it to squeeze. Good idea!