So it seems I was too quick to reccomend PST tailshafts as mine has unforunately failed. The carbon and ally tubes have separated, giving all the symptoms of a failed clutch. There is no visible breakage but there is a very loud screech/vibration that resonates through the bellhousing when the clutch is engaged under load. I can only conclude that sustained heat has caused the resins used in the bonding process to melt. There does seem to be some residue on the shaft. The slippage described is actually visible, I will try and get a video up in the next couple of days. Unfortunately for me this leaves the car decomissioned on a trip to QLD while I wait for a new one piece to get made up. I have emailed PST to see what they have to say. So yeah, as far as I'm concerned PST can no longer be considered the "good" c/f option. I would only consider chrome molly or steel for a replacement.