Look at the Vandersteen website where the complete manual for the Quatro is located. These speakers require every bit as much setup as any Vandersteen speaker and do benefit from being away from the wall. Imaging and depth will suffer being too close. You need to follow the setup instructions as close as possible. If you don't, you will never hear what these speakers are capable of.
My Vandersteen's are 52" out from the rear wall. As you move them closer the bass will become somewhat diffuse and ill-defined. The controls on the back are for frequency deviations in the room (room effects) and will not adjust out boom and other near wall problems totally. However, as I said, the bass is not the only thing that suffers in too close to the wall locations.
I've listened to the 803D speakers numerous times and chose the Vandersteen's. The B&W are excellent speakers and I can certainly see them not being close to the wall. I did not really care for their sound honestly (personal preference.) I just thought the Vandersteen's threw a bigger sonic picture that seemed ( for the lack of a better term) more accurate in their portrayal of the sonic picture. Too me, B&W has always had a certain sound that is pretty consistent across their line. I use to call it the Kevlar sound but I'm not really sure what it was. The Vandy just sounds more natural to my ears (when it is setup right.) Otherwise, it will sound very average.