IMO the center sounding better is likely because in many recording both straight audio and also video mix some of what would be center channel information into the mains to help them blend better and also because sound engineers know that most people have better main than center speakers. An extreme example is the demo 7.1 Blu-ray DVD that came with my Oppo. Nearly all of the front audio is coming from the mains and only a little reverb is coming from the center.
P.S. Stick around and represent the M50 crowd here on the forums since they are a bit underrepresented.
