I still think that the best solution is the Ebay one. Vote per user, positive, neutral or negative (default is neutral) with a comment. This can be changed at any time, and anyone can view all the comments sent to a user as you can see a seller/buyer's rating at ebay.
Here I made sample screenshots and all:
http://shoutbox.menthix.net/showthread.php?tid=20...d=189947#pid189947