A mechanical encoder? No, I don't like that at all. How many parts will be exposed when the cover tape is lifted? Do you have a blade or cover to keep the parts from jumping out of the tape pockets? This is a REAL problem in P&P, see comments in manufacturing forum section, where P&P has been discussed a lot.
My CSM84 feeders have no more than 5 parts uncovered, and the clamp covers 4 of them, and the retractable blade covers the most forward one until the nozzle is about to make the pickup.
Jon