My Pioneer does some magic with 5.1 material for the 7.1 rears. I don't know how much of an impact it makes, but there is sound back there. For EX content, it is very impressive, but again, it really depends on the content - some is great, some not so.

-Brian

2xM60ti, 2xM3ti, 2xQS4, VP100, EP350, N2's