BMX: the DynaBoxs that I recommended him will prevent any of that bleed into the room above. It literally absorbs about 90% of the backwave while improving the sound coming off the front of the cone as well. Worth every penny!!
Oh yes, I would definitely agree with that. If there is a way to build in boxes, or put those in, then it is well worth it. Even moreso if there is potential for bleedover to other rooms that needs to be avoided.
I haven't checked pricing on them, but I have heard they are pricey.
Still, I've replaced B&W (and other) in-ceiling speakers with Monoprice speakers, and have had a significant improvement in audio quality and output which leads me to believe that there tends to be very little difference from one in-ceiling to another except for overall build quality.