Irv,
If a pair of 12" Rythmiks weren't well under half the price of a pair of 12" JLs, I probably wouldn't have gone there either - home trial or no home trial. Buy, unpack, set up, evaluate, re-pack, re-ship a big ass box...maybe not.
However,.....
Once I decided to commit to quality subs in my system, I auditioned a sh*tload of subwoofers (most on more than one occasion) over the course of 12-18 months. The results of those auditions varied widely (as did the quality of dealer demo). The variability of subwoofer set-up care, demo system, demo room, etc. really hindered my ability to reach confident conclusions re: relative subwoofer performance, model to model. At the end of the day, I thought that the JLs were the best of the lot. But they were also the most expensive.
Since I also concluded that in-home auditions would (for me) be the only really dispositive tool in evaluating a subwoofer (much like any other component, I guess), I knew that I was kinda stuck with the "buy, unpack, set up...." rigamarole, anyway. So, given the price delta...
Either way, I'm pretty confident that, in a carefully set up system, (ie, with some sort of controller, Audyssey or other), a pair of the the appropriate (to room size) either JL or Rythmik subwoofers will do a GREAT job in the bottom octaves for those want to go the subwoofer route. Other brands may work marvelously, too - I just can't really make that statement that from my own (necessarily limited) experience.
Marty