Corner treatment -- PZCs a sure thing?

I'm looking for a set of room upper corner treatments for my living room. The upper corners probably are the only places in that space where I can use audio-specific treatments. The triangular pillow-type traps seem like a pretty sure thing; it sounds like only good can come from reducing the amount of energy being megaphoned out of those corners. I'm not so sure about the tunable pressure-zone controller devices (Michael Green). Are they as versatile and sure to be helpful as the pillow traps? Can anyone describe the comparative effects of these two approaches in their room and system?