I haven't heard any RELs. I did hear JL Fathom F212's--a pair of them meticulously set up with a pair of Magnepan 20.1's. It was a superb setup--great integration, great timing, great control. And it wasn't all boom and sizzle. We spent most of the night at the demo spinning LPs on a DPS/Ayre turntable. The JL can blend with first rate panel speakers and provides good bottom for a high resolution nuanced performance. They can also, of course, kick ass.
I can't say whether the REL or JL is better per se, but I have a great local JL dealer and I've heard the JLs under challenging circumstances. And if I had the coin for a take-no-prisoners sub, it would be one or two JLs.