In mulitplayer Guardian is a must. Falling away is nice but the chance of getting hit 2 or 3 times with FA is to great a risk to not have Guardian in.
In 2 player I always play with a strong defense so if my opponent is getting by me easily then having FA is only going to prolong my defeat where as Guardian can keep me in the leed if my offense is working well.
With those being said I always put both in my decks unless I'm trying something radical, which if you know me doesn't happen very often.
