am pretty sure awesome gti and a robert (one of chap on here) said the Helix was better, but am sure plenty of people who have the sachs may feel different...
i need to ask the same question and carry it further by asking which is best LSD to go with one of the above clutches...
I have the Helix on my stage2+ ed30.
It does have a higher torque limit that the Sachs equivalent but I'm sure both are more than up to the job.
Price wise, the helix when I had mine fitted 2 years ago was cheaper than the Sachs but things change.
I've not driven a similar Sachs equipped car but the Helix has perfect road manners being only marginally stiffer than standard but not in any way a cause for any fatigue.