Interesting thanks. I've not had the need to - or more precisely - not felt the need to, as we had carpet and lots of wall hangings. But since renovating - mandatory open plan, wooden floors very similar bifolds to you (how scary was the steel/lintel going in for you?) etc, the sound has completely changed - and i feel these may benefit. Did you feel you needed the depth - or was that for aesthetics?
Excellent - thanks for the comprehensive reply. I think i get the general gist and the A/V comment makes sense - and is noticeable in pic (softens the look too). My wife may want to play with colours though so i may lose on that score...
Cheers,
@ThereIs0nly0ne - you've saved me from making more holes in my freshly painted wall. But the biggest bonus is accessibility - such a PITA upgrading cables or if something fails with channels.