I may want extra 'wide' channels, but no 'height'.

I tried several Audyssey DSX receivers/processors and filled (literally!) my cinema room (a bit under 7x5m) with speakers up to the (divorce) menacing full 11.2 system.

My experience is this: going from 5.1 we all know/use/enjoy...
-a second SW makes biggest difference
-then the extra wide channels (yes! like super-Trifield width!)
-then the extra rears (our also 'usual' 7.1) but this depends on room/listening seat distribution
-and last will be the height channels. My room has not very high ceiling (2'7m), so maybe in a different room this may change too.

Audyssey blurb says something on the lines of 'we focus our hearing more in front of us thus there is where you want to put more sound sources'... and I think they got right.

This was my experience with Denon and Onkyo receivers, and btw 'she' agreed when listening, but was NOT happy at all with the sight of L+R+C+LW+RW+LH+RW=7!! speakers in the front wall.

Regards,
Josep

Basement: Linn Sneaky DS, 568.2mm, ARS Sonum Gran Filarmonia, Ramallo Allegro.
Living Room: 602, Linn Akurate DSM, Hypex Nc400, B&W 802D.