....Thanks. Great questions.
Basically the BOSS is an acronym for Baffle Open Sub Shaker. So, basically, it's an open baffle which does allow the back pressure wave to cancel the front pressure wave to mostly reduce SPL so it doesn't interfere with your existing far field sub and near field sub calibrations. The BOSS is all about ultra-low frequency (ULF) response that can be mostly felt...called tactile response or TR for short.
Also, because it's an open baffle, the woofer can reach single digit responses very easily and will very little power...less than 100 watts per driver and in some cases less than 50 watts per driver, depending on what driver is chosen.
The BOSS driver does need a baffle of some sort to provide a mounting surface. But, that baffle can be as small as the outer diameter of the speaker or as large as one can construct it while keeping it very rigid.
The larger platforms (baffles) add additional TR to the experience because that bigger area also interacts with low frequency pressure waves in the room from the far field and near field subs. This "passive" forcing function on the platform combine with the "active" forcing function of the drivers mounted on the platform and result in a natural yet commanding response to ULF content in the source material.
The last part of the BOSS is the platform suspension. This completely decouples the platform from the floor below and allows it to respond on command from the drivers (active force) and pressure waves in the room (passive force). The more "floaty" the platform, the better.
The BOSS concept is basically trying to simulate ULF as we feel it in the real world....which is from below us as a result of some catastrophic event that just shook the earth below our feet.
If the driver is mounted to the chair directly with a small baffle, some passive ULF effects will be lost but the active ULF will still be present and still feel very natural as long as the isolators are between the chair legs and the floor. These isolators will still allow the chair to respond on command from the driver that's mounted directly to it.
That's basically the BOSS in a nutshell....everything else in this thread is just a variation of these concepts and retrofitting the BOSS technology pieces into our living rooms and theaters to accomplish other goals in the room (i.e.; risers, chair mounts for traditional fold-up theater chairs, aesthetics, platforms for mounting other traditional shakers and transducers, etc.)
Post 29 has the instructions for building a BOSS of your own along with a link for purchasing the isolators. Post 2151 has a list of speakers that have been used for other BOSS builds and reported as working well.
As always, if you have any questions as you start planning your BOSS design and build, just fire away.