The JL subs are the most musical I have ever heard. I was looking for a sealed servo controlled sub to best match my electrostats, btw. They provide the best transients I've ever heard from a sub as well. They also have as good, if not the best, pitch definition I've heard from any sub.
If music reproduction is not #1 priority, but HT is, I can see how an SVS could save a lot of money for similar, or better, extension and output (of course if larger cabinet is a non-issue).
I have never heard any product made by either SVS or Paradigm, btw.
So, out of the servo'd subs I listened to, I thought the JL bested Martin Logans which in turn bested the Velodynes. And yet, the JL was smaller and less expensive than the comparable other models, in my experience. Unfortunately, the JL's do not have hi-level inputs, and the grill must be taken off to access the on/off switch. When the grill is off, the insane excursion can indeed be a serious distraction from a movie.
Sending pm, BMW.