I always thought this would be a cool idea even for PvE. But I'm not sure about the cons it would have and how it would really effect ques.

As for feast, I was also wondering if it would be cool to have a separate rating for each class. For example your WAR could be a 560 Silver, yet your BRD is 231 Bronze. Also gives you a way to save a rank you're really proud of yet still queue up for games on another class. Blah blah blah