I have the folliwing system:
BV9; Penta-front; 6000 rear; Beolab 11 sub (1)
I added Beolab 4 as surrounds, and made the 6000's "back". 4's are on B&O stands
Nice thing was BS3 did not require reinput of distances for speakers already in. Amplitude was carried over as well.
I *like* the 5.1, EX and IIx matrixed to 7.1 for all sources and all materials. Period.
FWIW
Barry