If you get close to the speaker when it is playing even moderately loudly and place a stethoscope on the surface, you will hear much more noise (mostly in the bass and mid-bass) coming from it than from the cabinet of any really first rate speaker (B&W, KEF, Revel, etc). This issue is a major design target for most high and even not so high end speakers - an acoustically non-resonant cabinet. Given that this has a metal structure, the resonance is not bad and pretty well controlled, but compared to a top wooden MFB it is really not so great. I notice that the sound seems cleaner, but of course this could be just auto-suggestion. Double blind testing would confirm whether it is an issue, but I am happy with the now totally inert surfaces that I have on my 3.1s.
best, Doug