Common Review Date

I'm interested to hear from those who have converted from an anniversary date performance review/merit increase to a common review date/merit increase. I"m most interested in lessons learned from the initial conversion - that is, how you took care of the salary increase issues - dealing with pro-rated increases. Did you find employees "just didn't get it." ?
Comments
See prior conversation on this as well:
http://community.blr.com/hr/forums/thread/5830.aspx