The only problem I have with this is that sometimes people only win because one or two players on their team, not because they played with skill. For example, one time I was playing Team Slayer and I scored 25+ kills (can't remember the exact number). I practically carried the rest of my team through the match. Winning should get you extra Exp, but (just in my opinion, of course) playing well should still get you Exp if you lose.