Eric,
He was asking about our standard non-servo version.
The SW12B is a great woofer and easily can be compared to any commercial sub you can come up with in regards to sound quality. I have heard really good feedback from a lot of customers and have been told that they replaced big name brand XYZ quite often.
You may find some good feedback here in my forum just by doing a search on SW-12.
Another thing to consider, and this is something that a lot of people don't realize, is that a large percentage of the sound quality can be attributed to a solid enclosure. A well braced thick walled non-resonant box goes a long way. This is also where a lot of commercial subs fall short.