Mel appears to be everything Ed was not. He is kind, loving, nonviolent, and basically reasonable (though he should probably steer clear of the gin if he knows what's good for him). Ed was abusive, violent, and, uh, nuts.
While Mel might not always be awesome, Ed's behavior makes Mel look like a saint. On the other side of the coin, Mel's detachment from his wife (he even says they would do just fine if they lost each other) highlights Ed's passion for Terri. And it also hints at Mel's possible depression, which sounds eerily familiar.