Is it the 'torx' fixings? thats what we call them anyway. We've started using them for fitting uPVC windows instead of frame anchors. They're 7.5mm diam and we just drill a clearance hole of 6.5mm then the screw threads itself into the brick and they're rock solid. plus the head is a torx bit so there is less chance of the bit slipping. Stu
I'm assuming you're talking about these Multi-monti things Screwfix are selling. Mine were ****, half of them sheared. If they can take the torques required to get them into the hole, they're probably quite good.
I think it depends on the density of the bricks themselves, I used to live in an area of the country where the bricks were quite soft (yellow stock bricks) I've now moved to a different part of the country & the bricks here are hard as stone!! On a 8mm hole, a cordless (18v) hammer drill is pathetically useless, a 750W hammer drill gets there slowly so I now use my SDS machine -ahhh!!- I doubt if you could use brick screws in these bricks!