Firstly, thanks Dave for your answer!
Then, about the deal on the discs, I bought some other ones (from you) almost 2 years ago and I will install them now. So I guess I'll need another set of discs in about 3 year's time
...
Because the minimal thickness is 23.4 I will definitely replace them asap.
The current discs have some cracks but they had them from day one (aka after the first track day). I think it's normal since they are not too big.
I might consider a service but it is a little bit difficult to have the calipers removed, sent to UK and vice-versa. I think I will do this maybe in autumn.
Yes, the nqsbbk has done an amassing job. Excellent pedal feel, awesome for daily drive, great for track days for my 160bhp 1400kg Golf. When buying it, I think I spent 1000 GBP (calipers, pagid pads, discs), so not quite cheap but great value. I am only changing the discs after 3 years and the combined value of the discs and pads used over these 3 years is less than the discs for the Stoptech BBK, for example.
I think the brake ducts also had an effect (not sure if large or small) so I will keep the nqsbbk + Pagid Yellow RS29 + J Hook Rotors + brake ducts (there was a design flaw with the brake ducts that will be taken care of, hopefully, this weak; I will explain in the brake ducts topci) for the current year.
All the best!
P.S. My friend below was really, really impressed with the braking power of the nqsbbk.
If you follow his head closely you can tell if I am braking or not
My friend said I should install a hans device to prevent the passenger from straining his neck muscles