I reccomend XBMC & Plex server together.
I use
http://mymovies.dk for my whole library organization. (with enabled .nfo files for XBMC to scrape) Plex seems to pickup everything no problem as well. The key is having folders & files named to perfection.
I have multiple 3TB drives "pooled" into one giant drive thanks to
http://stablebit.com/DrivePool. This means I only have 1 "Movies" folder and 1 "TV" folder to worry about.
I use combination of Windows Media Center (Windows 8 on my 2012 Mac Mini) & XBMC Frodo for my front end 10 foot experience while at home. I use Media Center for my Ceton CableCard Tuner DVR recordings. (since I'm not confident in XBMC PVR options yet, and the new HDHomeRun h.264 Prime isn't out yet)
I have Plex Server installed and use that for viewing via iPad/iPhone on the go, and can Mirror my output to friends Apple TV's or their XBMC setup.
For me that's the perfect blend. Everything is auto sorted and named to perfection via
http://www.filebot.net/
MyMovies database is Fantastic once you set it up.
For my needs, I don't see the benefit of hassle time messing with plexbmc. I'm ready to try a new PVR solution other than Media Center in the near future though. (Microsoft officially abandoned it recently, but it's still king as of 2013)