Rear Channel fill

I have to start out by saying I was in high school, when the 4 channel or quad hi-fi made it's debut.  The discrete quad was very different, but appealing.  I remember in Nashville, on WKDA, they would broad cast the Quad hour.  That's not what it was called, but close.  Of course it was nothing like the quad LP's that were sold.  Real quad is mind bending.  Alas-no more.  Now, the debut of 5.1 surround, has let dad or husband get pretty good sound "for the family."
Sometimes, I enjoy adding rear channel speakers, at a low level, as "fill."  Some say they want to experience the live concert experience, but the only concert experiences I recall, that were of great quality, were classical concerts I had to attend for school.  In the right venue-wow.
I mostly listen to old classic rock, some hybrid bluegrass and progressive jazz.  About the only thing I can say about live rock concerts is that some of them, when mixed properly, are ass kicking, as far as sound that drives me into my chair-when sitting down,  Anyway, sometimes I like to add a little rear channel fill.  Am I alone?  I've had some say I'm not reproducing the "real' concert sound.
I dig it-occasionally.