brianslides, if you had the opportunity to directly compare a properly positioned JL F113 with any REL in your system, any pressure you're currently experiencing would be replaced with an eyebrow raising at the reading of woots' waxing.
I did it with a then new $10K Studio III and an early F113.
I believe JL Audio has since remedied your concerns. The F113 was every bit as potent as the Velodyne DD-18 which was also present during that comparison.
I strongly suggest shopping for subwoofers that offer remote volume control. Equalization or optimization presets are another very usable asset.