i agree with Apognophos.....i train with many fighters pro and not pro. It is not staged, i believe the difference between mma and boxing is, if the ref see's a fighter in a compromised position than the ref will stop the fight. take the last benson henderson fight.....great refing.
I do believe it is a lot safer, when i roll or spar during training no one goes out for blood. usually if someone comes in for blood they will be kicked out of the gym. I have seen it first hand.
like i said it is a true friendship that is developed. the great thing about it is....if you don't believe what the other guy believes you are not ostresized.
GTTM