Stewart from Sanders web-site:
"Q. OK, I see the advantages of narrow dispersion, yet what happens when I leave the "sweet-spot?"
Sanders Sound Systems speakers are designed to bounce the ESL's
rear-wave off the wall behind the speaker where it can spread out and
fill the entire room. As a result, our speakers sound about the same
off-axis as conventional, wide-dispersion speakers. When off-axis, you
won't hear the precision image you do at the sweet-spot, however, the
sound is quite satisfactory for casual listening or even for
home-theater use".
(dealer disclaimer)