I personally think it took a great deal of honor for Benedick to stay behind at the wedding with Beatrice and Hero, rather than leaving with Don Pedro and Claudio. It would have been the "manly" thing to just leave and stick with his cronies. Instead, he stays to see if Hero is okay (probably to make sure Leonato didn't do something horrible to her), and I don't believe he did this simply because of what he saw Beatrice do. He may have done it partly out of love of Beatrice, but again, that shows his honor in choosing her over his war buddies.
I often wonder if Margaret knows what happened and kept her mouth shut, with regards to Hero's disgrace. I've seen the play performed both ways - where Margaret IS at the wedding, but doesn't say anything out of fear of getting in trouble, and also where Margaret is NOT at the wedding and just has no clue as to what's going on. I'd like to think she didn't know, but as close as she was to Hero, wouldn't she have figured out the mistaken identity and confessed to clear Hero's name?