I would not switch either. With the JL Audio you are paying a lot for room correction and a calibrated microphone. Room correction would be much better handled with a good DSP unit and REW.
JL Audio Fathom
I've been very tempted to upgrade my 2x 12in Martin Logan 1100x subs to 2x JL Audio Fathom v2 subs. for reference the 1100x retail ~1300$ and the JL Audio 5k. I am very happy with the Martin Logans which are very nicely integrated with my Sabrina X speakers. Do you think it would be worth upgrading to the Fathoms?
No REL for me because I don't want made in China FYI.