This guy makes some good points about the KEF KC62 but doubts the numbers (specs) KEF has put out there, simply because of physics. I'd have to agree.
But it's not all negative as he points out and it could be this technology they've developed may lead to a downstream pass-on to their bookshelves/towers, which will negate the need to buy a subwoofer(s) and the space they take up.
I know it was a conundrum for me and I finally settled for a pair of SVS SB-2000's.
Window rattling? No but good enough for my ears, without having it breakup at lower frequencies. The Salk towers do great job digging (down to 32Hz) and the SB-2000's do a fantastic job of filling out the soundstage down to 24Hz, which is more than adequate for music, even for organs or the rare occasions I listen to rap.