[tebasuna51]

Of course everybody can test anything and select their preferences.

I can understand some coeficient variations if Ls,Rs speakers aren't at -+115º, the average of Lss,Rss -+90º and Lsr,Rsr -+140º
It is well know than we need only 4 speakers (FL,FR,BL,BR) to create any surround sound 2D with the appropiate mix.
The 7.1 systems were created for commercial purposes, the 5.1 is more than enough for 2D surround.

But include other back channels in the mix of Ls,Rs is out of my mind.