To the best of my knowedge I think they use the same cleat being that they're almost the same pedal. I had a set of Miche' with a floating cleat. I used some old toe strap loops screwed into the plastic part to add some security for hard sprints.
Re: numbness. Loosen the bolts holding your cleats so theyre able to move a little under pressure. Go for a toot around the block and carfully undo your shoe leaving it on the pedal. Mark the cleat position and tighten it down.
The common mistake with fixed cleats is to point your foot dead straigt. Your leg normaly doesnt like this, espessialy if you stand duck footed. When you used a fixed cleat your pressing your foot's side against either side of the shoe hard!
You'll find alot of people who've suffered that problem now run speedplay zero's due to the multi adjustability. Eventualy you learn to spot how your feet like to angle. Try setting up clip and strap for feet that like to point out.....now thats a pain!