Just a quick update.
I heard back from the UK Pagid distributor, and they've said that the pad shape 8091 (front) and 8270 (rear) will fit in pad compound RSC1, 2, and 3. RSC1 is suitable for all carbon ceramic applications, whereas 2 and 3 are a more abrasive pad, but which one you use depends on the construction of the disc.
I've since talked to one of their retail distributors (performancebraking.com) who have quoted:
8091 RSC1 £544.99 +vat
8270 RSC1 £349.47 +vat
I don't need rears right now, but I'm going to get a set of fronts ordered and see if they fit. It's a big saving over the OEM Brembos.
What I'll likely do is run these until nearly ready for replacement, and then swap to an all steel setup (likely to be OEM Super Performance on the rear, with a big brake setup on the front from Alcon or similar).