I disagree with this. Class limits are a bitch, particularly for players that actually should be playing that class. There shouldn't be anything stopping Photek from going sniper and owning my face. From my experience, when teams are unbalanced it's because of an imbalance of good players, and class limits won't fix that.
A sniper/spy who can't figure out teamwork or contribute in any way generally doesn't do much better when they change class.
All that said, I feel your pain Jever. I just don't think class limits will solve the problem.