REL vs JL AUDIO

I've owned JLA, Rel, M&K Martin Logan and others. I've heard SVS, Rhythmik, others. The best combination IME which I currently own are JLA Fathoms with an outboard Jensen high to low output converter. 

Also, any sub can be difficult to integrate if you don't know how, and without measuring to aid with dialing in, it's nearly impossible to get seamless integration. Then of course, final tuning with your ears. 

Both a very nice.  I have had no problem integrating my JL Audio f112 in my 2 channel rig.  No negative resonance issue(s) or anything else that I can report.
Simply great low end!

Just a thanks to everyone for all their input. I am at this crossroad right now deciding on Rel or JL.for my Monitor Audio pl300ii's.  Prior to the 300's, I was using Klipsch Forte's with an SVS sb1000. Now, the SVS just doesn't cut it musically with the 300's. Hence, I'm leaning toward Rel but have heard good things about JL subs as well. So thanks for the read folks, cheers. 

manelus, I hate to be a stick in the mud (ya right) but, speed has nothing to do with it. When a driver can not move fast enough it's high frequency response rolls off. Look at the frequency response of the 18" Dayton I mention above, 20 to 500 Hz. It has no trouble putting out 500 Hz so 80 to 100 Hz is not a problem. Most 12" drivers make it to 1000 Hz without issue. It is usually not speed that cuts the drivers off either but cone breakup. So, then what are you hearing? Transients and detail are being smeared because either the subs were not well match to the main speakers or the amp driving the subwoofer was not able to control it well.
Driving big powerful subwoofers is not easy. There is a lot of back EMF.
This is a problem we noted way back in the late 70's when subwoofers were a brand new deal. Some amps made great bass others not so much. Basically you need a lot of power (big power supply) and an output stage with extremely low impedance. The class D amps that most of the Subwoofer manufacturers are using usually do an admirable job but IMHO not as good as a big class A/AB amp. But, in a small enclosed space you can't have a big amp that generates a lot of heat.
By the way, if vibration affects electronics why are we sticking amplifiers in subwoofers? Just a thought. I prefer passive subwoofers and outboard amplifiers. With outboard digital bass management there is no need to place electronics in the subs. You can then pick the amp you think makes the best bass.  As far as matching subs to main speakers is concerned, the vast majority of sub owners are not able to do it correctly because they do not have the tools. Doing it by ear is folly. It's like pinning the tail on the donkey. It is easy to do if you take off the blindfold. Using a measurement mic/program along with digital bass management allows you to dial it in perfectly every time regardless of where you place the subwoofers and boy do you get big smiles when everything is working right. 

Subwoofers are neither fast nor slow. They are either driven and integrated correctly or they are not.

Don't get me started on enclosures.

2 for the REL CARBON SPECIAL!!! Thats where I'm leaning!! one to start, they aren't cheap. REL for the win!!!