I had one of the first Velodyne F-1800 Mk. II monster subwoofers with servo-control a monster amp and 30+lb 18 inch driver. Never-again for audio, theater doubtful.
You can buy whatever kind/quality sub you desire these days but the old 'boomers' are not as popular as newer subs seem (less blurry) more musical/tighter (if you want). There are still plenty of big ported subs for theater boom.
I believe subwoofer technology has increased far more in the last fifteen years than that of other audio devices. At the same time prices have plummeted for quality inexpensive subs. (Hsu, Rythmik, SVS, etc.)
With DSP and a fair set-up, I think most would be amazed how great a Swarm 4-sub setup can sound as opposed to one big old sub of days of yore.
But OP, your ASW2000 is a very fine sub so I understand where you remain!