If this sub cost $500, I can see it being a really good sub... for the money. At $3K, though, I'm at a total loss as to why anyone would buy this product.
Given its performance, yes, it is spectacular down to 40Hz, but, down to a low B note (31Hz), the THD becomes so prominent that it is no longer a low distortion transducer. While this will pass muster for a movie, it will not cut it for music. That much distortion will add a lot of color further up the spectrum and muddy up the sound. Playing a 5 string bass through this sub, you aren't going to be happy. I know I wouldn't. Also, a kick drum tuned very low will not be rendered well.