I just purchased a pair of REL T5x and like @Pooch2, I was very pleasantly surprised at how easy they are to set up and dial in.. The REL’s work wonderfully with either my upgraded/modded MMG’s or Sonus Faber monitors. Integration with either the little Maggies or the SF’s is seamless. I’ve had a number of subs before these, including REL T5, but the T5x’s are by far the best in my experience.
I followed REL's setup suggestions closely and am thrilled with the results.
Sure, this is just one guy’s experience, but I do hope it helps some of you other guys and gals.