I would keep the line array radiation pattern through the bass and build an array of 12" woofers. You could put three-four 12" woofers in each column .. separate from the mid bass to avoid bass vibration effects.For HT, I would build a 5.0 setup to maintain stereo bass ... no summed woofers. This would give you the best CD/SACD stereo sound. Many DVDs sound much better with the rear speakers set very low SPL or off. Very few rooms are large enough for great 5.1 or 7.1 with normal furniture.