I don't understand how it is a good thing to be able to stick multiple navigation relevant tags to a post. Even with a limit of 5 I see a incentive to add a few non-relevant but popular tags, just for fishing in those channels as well.
As reader I'm annoyed when having to go thru all the tag spam when exploring a subject. wouldn't a single leading tag force to choose a relevant tag and improve navigation? Or am I missing something fundamental?