I recently got a couple of the Festool centrotec 6mm masonry bits (I didn't buy the set, just the 6mm) and they're great. I've used them with my PDC18 for drilling tiles (awesome results, apart from the water pipe I drilled into [embarassed] ) without the hammer action, and for drilling a few different types of stone/brick, both with and without the hammer action.
There's just one problem with them - they're WAY too short. You can drill a hole about 60mm deep, but that's your lot!
I want Festool to make longer versions, ideally about 150-200mm long. The existing ones are fine if you're drilling straight into the wall without anything in the way, but if you want to drill through a cabinet, through plasterboard that's been dot & dabbed, and into the masonry behind, you've got no chance!!!