I have had several demos of the 1812 and came very close to purchasing one (@60% off of MSLP) a few years ago.
At this point, it would be more of a novelty buy than any serious subwoofer purchase. There are too many better performing products @ a much lower cost than the $5-6K prices you see the 1812's advertised for on Audiogon.
Still, it is a very cool looking and great sounding sub and the build quality is the best I have ever seen (including the Gotham).