I'm not a huge fan of the design, because they can only really play up to 120hz or so. For a 2 channel system this is fine, but for one using a sub crossed at 80hz it's not really worth the added cost and design complexity IMO.
Perfect example would be the NHT Classic 3
, which normally goes for $800 pr. This is a 3-way monitor with a 3/4" tweet, 2" mid, and 6.5" woofer. Then you have the NHT 4 Tower
for $2000 pr, where the only difference is 10" side firing woofer crossed at 125hz in a large tower configuration. To me that's not worth $1200, not when I'm running dual 15" subs taking over at 80hz. If this woofer was front firing, and crossed around 300 hz then there would be benefits like greatly improved mid bass impact, and lower distortion.