when i used a rptv, i used the horizontal, but after moving to the front projection, i have exclusively used a full range tower speaker. I have used it below my screen when my room allowed and currently use it behind my screen. I believe most of the early designs are based on sitting on a traditional tv or RPTV as it was difficult to figure out how to put that big tower speaker or even small monitor around the center without taking away from the aestitics of the "theater" effect.
