Lol....as someone who plays both monk and ninja (cleared t9 as a ninja and cleared t13 as a monk)all I can say is good players will be good. Bad players will be bad. If you are bringing someone in your raid group just because they play a certain class over someone who is better but doesn't play the class you want, well you're doing something wrong.
Skill>class.
Oh and please dont be a smart ass and say, "then I can bring liek 4 drg or 4 smn or 4 *insert class here* hurr durr" you know what I'm talking about.