I'm looking for information about the Genesis Servo 12 subwoofer, which was made by high-end speaker company Genesis Technologies beginning in 1991. I tried contacting Genesis, but it appears that the company traded hands (hence the new name, Genesis Loudspeakers) and lost intellectual property in the process. The original MSRP was $1,600.

The only information I've found has been from auctions, so I can't post links that have pictures of the subwoofer. There is currently one for sale on eBay, if seeing the item will help with its assessment.

I understand that a lot of changes in subwoofer design have occurred since the early '90s. How would a subwoofer like this compare with newer designs with class D amplifiers, etc.?

Some of the older Velodyne subs of that era are still pretty good by today's standards. But, everything has come so far that buying something from 1991 for other than sentimental reasons is not the best idea where performance is concerned. You can buy something that will be equal to multiples of the that design for about the same MSRP.

If you still desire a small 12" servo, you can probably get a Velodyne DD-12 for a reasonable price which includes on screen equalizer...