Err, so how is it superior again? My Genesis 2 and Saturn use the same output... so I can get a Sat A/V (or perhaps even S-video, not like it would matter) cable and use that. Besides, if a game has mono sound it will always have mono sound. It will spit sound out on both speakers of course, but it'll be the same sound.
Well, I guess having one AC adapter could be a plus, but I have plenty of plugs for all my systems anyway.