I can say this.... When I took my E92 to the Ring (running Marcel's old drilled and vented disks, with new cool carbon pads and standard calipers) the brakes were cooked within the first half of the lap.
That said, there is a big difference between 'a few track days' and 'the Nurburgring.' We might all go straight from nothing to Nurburgring, but that doesn't mean we should be. It might be that my setup is perfectly adequate for Croft, or Knockhill. I basically agree with Phil, in that actually for day to day motoring my setup is more than adequate.
It's worth noting that when we went to the 'Ring, the ambient temperature was 38 degrees, so the cars were struggling to cool everything really and IAT's were high.
Anyway, I will be interested to hear your thoughts Idnan. Few others are as well placed to test the PB's in anger as you are and so I expect a full report to benefit the rest of us. On the back of that report, perhaps Dave's or my opinion might change and I am sure a GB of as few as 2-5 units will attract some discounts, when you take into account how hard PB are having to push to break into the UK BMW market and the reknown of this forum.