Is it better to have two matched subs or one

@dbphd I've had the same experience with all the speakers I've had in my room, I didn't mean to imply that the Ref 1s were doing something others couldn't, although they do image better than any other speakers I've owned.

More is better unless you can't afford them or don't have room for them.

Subs don't need to be identical.  I have two Rythmik subs and two SVS subs.  I have them set up in stereo, but I don't think it really matters.  They're all over my room... in front of me, beside me, behind me, facing into the wall, away from me...  I have relatively small monitor speakers - the KEF Reference 1.  I have no trouble identifying where the bass player is standing on most recordings because they provide all the cues I need and build a solid soundstage with great imaging.  Listening to the alternate version of Fleetwood Mac's Rumours I could picture where John McVie was standing.  Now when I play something like Deadmau5 or Bassnectar, the bass is everywhere.