CNC Clutch Master Cylinder

[csx4017]

I would like some feed back on your experience with the CNC Master Cylinder when used in the clutch system. I presently have my third one installed. I have been chasing a clutch actuation failure mode. For the second time my clutch pedal has gone to the floor during street driving conditions. The first time I jumped on the Tilton hydraulic TOB as the issue. I replaced the 600 series with a 6000 series without firm technical rational. The TOB piston was not leaking. During the replacement the system would not bleed and the master was changed out. Went from an aluminum 3/4 to a steel 7/8........System bleed and we are back on the road. Second failure ( with exact non return of the pedal ) is in the process of being repaired.
History:
1) The CNC cylinders seal showed signs of damage ( nibbled edges )
2) 600 series Tilton did not leak
3) Do not have firm evidence that the 6000 series has leaked either
4) Thought about going external and eliminating the internal, again without firm evidence that it is the failure mode.
5) Waiting for the results of trouble shooting of CNC master.
6) Experts in the external, internal and Tremec TKO600 trans indicate that my issue is not with the Tilton TOB.
7) My long input shaft Tremec will not accept an external kit because the fork will have interference with the bellhousing/ pressure plate.

Present thoughts are to stay with the internal unless firm evidence shows leakage. If the internal is good then we have blown time and $$$ on overreacting and jumping to conclusions. Should the master cylinder prove bad then pulling the trans was wasted time.
Good news is the Kevlar clutch show no wear.............Any technical comments ??? Nick ???