I went from 6.1 (had a corner loaded layout and needed the rear channel to fill in the gap between Left Surround and Right surround) to 5.1 with a much better layout, very similar to yours and I find the 5.1 equally satisfying as it is layed out properly, no odd placements of surround speakers. I have yet to try the rear channel out in the new house, it would be about 2' behind so it might still work equally as well.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70