We used 3/4" pan head #10 sheet metal screws for most things like this. You can coax them into a metal stud through drywall and they are not coming out of wood. Most of our low voltage stuff was on 3/4 plywood. You do need a drill/driver for the metal studs but I assume most guys use them anyway. I used to buy them by the 5lb box at the fastener store and split them up with the guys.
They provine a lot better bearing surface than the bugle head deck/drywall screw.
