Why not try torx screws?
They are far easier than pozidrive.

Agreed. Torx heads are excellent. I use the 6mm multimonti masonry
fixings with torx heads. They're available in some sizes from spax -
I'd be pleased to see them become much more widely (and cheaply)
available.

Currently looks like a 50% price premium:

http://www.screwfix.com/app/sfd/cat/...43574&id=15276
http://www.axminster.co.uk/product-S...rews-19753.htm