@danimaz, If you reread my post above, you will notice I did NOT state that I prefer Rythmik over Hsu and JL. I brought Rythmik to your attention firstly because you responded to mzk’s post about the Rythmik F18 by saying you are not interested in an 18" sub. Okay, Rythmik also offers, as I said, 8" 12", and 15" models. Secondly because I thought you might be interested in a line of subs priced in the neighborhood of Hsu’s, but with sound quality more akin to that of JL’s. If I was mistaken, simply ignore Rythmik. If you ever hear one, I suspect you will regret having done so.
To answer your other question, yes I own a Rythmik (four, actually), as well as a pair of Hsu’s and KEF B139 woofers (the legendary driver used by Dave Wilson in his WAMM loudspeaker) in transmission-line enclosures.
You state you heard of Hsu only recently, and did so in the process of researching the JL’s. Hsu’s are fine subs (and designer/owner Dr. Hsu a great guy---I met him at CES in Las Vegas, and picked up my Hsu subs at his facility), with many satisfied owners. So are Rythmiks, and reviews by their owners can be read on the Rythmik website, as well as on various hi-fi forums.
Rythmiks, like Hsu’s, are sold directly to the public, with a money-back trial period. Look to see if Salk Speakers will be showing at AXOPA---Jim builds the Rythmik Direct Servo-Feedback Sub into his higher-priced loudspeakers. If he is at the Chicago show, see if he is demoing any of those models.
In your post you state the sub(s) will be used 75% for movies, 25% for music. While maximum SPL at very low frequencies is not the highest priority for many listeners in a music sub, it generally is in a home theater sub. The output capability and reach into lower frequencies of an 18" woofer is considerably greater than that of a 12" or even 15" woofer. You can buy the 18" Rythmik sub---either in a sealed or ported enclosure---for less than the price of a 12" JL. Something to consider.