We install more in ceiling subs than anything else. In high end custom homes without a cabinet to hide a powered sub (which is really the best) we often use the Speakercraft in-ceiling sub. The thing I wanted to add to this thread is that getting the ceiling sub in the corner of the room produces a much more dramatic bass response other that putting it more central to the room or between the rears (especially if the sub is just going to be wired passively).

Jeff