[quote=@Kibaro]
what are your guys opinion on the matter that the GM could/should also play a character (not NPC but PC like the other members) in his story, as long as he is fair with it? :)
[/quote]

In the campaign I'm currently running, I like to throw in DMPCs for short stretches. Maybe the party runs into them while hunting down a dragon, or happens to find them fending off some creatures on the way to a destination. A good way to introduce unused classes to the party at the very least.