Re: Aikido. Effective?
Used it many times as a bar manager and for event security.
I do DT for LEOs and they love the application of aikido for their needs.
There are Tai Chi folks that can whoop some serious butt, and their are "mixed martial artists" that can't punch their way out of a wet paper bag.
IMHO, I think many times it comes down to the artist and not the art in question.