The slave piston comes in many colors...thats no big deal. Extending he slave rod is only a band aid fix. Adjust your clutch master by threading the rod out of the pedal assembly more. But to me, it sounds like your fork/pivot ball is worn. It wont effect the stock clutch much becuase it takes less movement to make it disengage. The RRE takes more so the adjustments and shift fork and pivot ball have to be in top shape.
RRE's Clutch And Flywheel Tech Info
Read the "other stuff" section at the bottom