May not be the only reason but it still smacks of adjustment issues. There are a variety of linkage sets for the 01E, are you confident that your whole setup from shifter to gearbox is homogeneous. I mentioned in another post that my setup with short shifter doesn't exhibit any of the issues mentioned here. I have a spare 01E with everything JHM offers installed in and out and the PO (who totalled his car) was able to set the quickest 0-100 times recorded for a tte550 equipped car, so shift quality cannot have been an issue either.

Over time people have mentioned issues with the plastic vs metal slave cylinders, deteriorating hydraulic hose, gearbox spacer issues and difficulty in adapting some clutch systems plus of course flywheel issues of all sorts.