i run a track car and used to used drilled disc as was lead to believe they would lose heat better but they didnt. they just got hot and wrapped due to lack of strengh in the disc where it had been drilled. i know it totally different on the road but i'd stay clear of them myself.
Racing and road use are quite different of course. But if you have a say 10" disc and you reduce its surface area by drilling holes in it therefore reducing the pad contact area. How does it improve the retardation of the disc in normal use?