6.5mm cancellous screws are routinely used to secure a solid fixation of the acetabular cup. I haven't been involved in a Total Hip in the last 15 years where cement has been used. Believe me, with all the torque and pressure put on the metal cup, you want that acetabular replacement screwed in.
I work in a small rural hosptial, but, over the years, I've done and seen a number of total hips.
Different systems, Zimmer, Depuy, etc have their own strengths and weaknesses.
Also, as with any surgery, pt selection is critical.
Over the past several years, different ortho docs that have come through, seem to me, to be using less and less screws in the cups.
Frankly, between bone cement and improvements in the cups, bio-ingrowth and all, cement/press fit seem to work just fine.
Never say never of course, the rep brings in the acetabular stuff when we do total hips, and I know he still brings screws along....just in case.