Let's take a step back. You seem to be holding your guard very high and I don't know why.
First of all, to defuse the conversation, I hold you in very high regards and think you do one hell of a job here. Your thoughts, ideas and advice I enjoyed reading and try to use and put to practice whenever I can.
That's one more reason why I ask YOU of all people, what do you think about the specs that KEF published with their sub. Those specs are bordering with impossible and I thought that precisely for that reason, they might raise your curiosity.
I'm sorry, I must have written it very poorly, I didn't want to say you are the one who made those "bald statements" as I choose to call them.
OK, I see now. I just didn't quite understand what you were saying. I thought you were saying I was making those statements about KEF's subwoofer. As for KEF's sub, it may well do +/-3dB down to 11Hz, but at what output level? That spec doesn't mean much. The type of design they are using requires heavy cones to produce deep bass, and that means low sensitivity, especially in mid-bass frequencies. No matter what, that KEF sub isn't going to be able to get very loud.
Traditionally those mini-subs used passive radiators to generate deep bass, like Sunfire, Polk, and Deftech's mini-subs. The problem with that was that the passive radiators had to be so heavy that it would wobble the subwoofer around. Also, they were never very reliable. Passive radiators that undergo high excursions tend to wear out. By going dual opposed with two active drivers, the KEF solves the wobbling problem that passive radiators bring. but taking two small cones and stuffing them in a small cabinet isn't great for deep bass output. So what they can do is weigh the moving assembly down for a lower resonant frequency which greatly diminishes mid-bass sensitivity but improves deeper bass sensitivity. Or they can just EQ for that kind of response, but if those aren't really long-throw 9"s, they will run out of excursion real fast in deep bass. Hell, they are probably going to run out of excursion in deep bass eve if they were extreme long-throw drivers. For every octave lower a subwoofer driver plays for the same output level, its excursion must quadruple. Unless it is strictly limited by the DSP, it will run into gross distortion very quickly in deep bass.
This is all just speculation since I don't know much about the sub. But it looks to me like audio jewelry rather than a real subwoofer.
