Just to play devils advocate a little, theres always a possibility the master cylinder was on the way out though and the road logging tipped it over the edge. ive personally never heard of a master cylinder failing. My octavia vRS was logged over a period of about 6 hours, and they had my fabia vRS for 2 weeks doing development getting it how i wanted as well so they would have both had that treatment, maybe more, who knows, and my brakes were 100% fine after for both of them. Initially thought it could be the extra power of the car, but thinking about it, it wont make difference either, as the 4th gear ratio in the GTI /ED30 is the same as the vRS, so terminal speed in 4th would be the same when the brakes are applied, its just you would hit that terminal speed faster.
On the plus side you wouldnt have R32 brakes if this hadnt happened
Think their new dyno is in the process of being installed now, so maybe no more heavy road logging, just a few tweaking runs on the road after.