I am looking at those ones:
http://cgi.ebay.co.uk/BREMBO-320mm-C...1%7C240%3A1318 It is a little expensive but you really get what you pay for. I have seen many Snowflakes brembo discs warping. I have recently bought some bargain brembo discs on ebay as well and it feels like one of them has a very slight warp. Most Brembo standard discs (non floatting) reach about £100 on Ebay, £150 / £200 for the cast iron (but you don't want that for everyday as they are rusting too easy). So £350 for the assurance to have a clean new set is worth it IMO. That's the next ones I will get for the ST.
I have a few sets of race discs (the style they use in BSB) on the track bikes and have not seen warping issues on those. Though some of those have centres that fit road wheels (the wide track one won't though), the rotors will only work with race calipers. On road 2 pad calipers, you need to trim the pads to make them work as they hit the bobbins otherwise. On 4 pad calipers pads fit fine, but the retaining bits under the pads hit the bobbins. You need to grind them a little to make this set up work and watch closely the wear on the pads so they don't fall off as a result.
Not sure how all this work with the radial calipers, have not tried those.