I doubt it being more efficient for a simple BB parser. Safer, definitely, because with regex you can say if it doesn't have a closing tag then ignore it. That way you can ensure every single tag is closed and thus not affecting the rest of your website.
As for the answer, well, I'll let someone else answer that :) ! As I know they are typing as I type this.
The man who comes back through the Door in the Wall will never be quite the same as the man who went out.