Specialized BG S Works shoes with Speedplay Zeros?

Are there any problems with this combination? I read a customer review of Speedplay shoes on the Wiggle site who said that his BG shoe rocked from side to side and gave him knee problems. I'm not sure how that is possible. Any experience out there?
Pegoretti
Colnago
Cervelo
Campagnolo
Colnago
Cervelo
Campagnolo
0
Posts
sounds like they messed up the fitting
perhaps it's related to amount of float used, i can imagine riders with a lot of float who rotate their feet might have a grinding action on the pedal body, i've got mine set for fairly narrow float
Giant TCR 2012