Here's my biased viewpoint. I own a vintage pair of Sound Lab A3s and am enthralled with how good they are every time I listen to them. After owning a dozen dynamic speakers including Quad ESL63s, Thiels, Vandersteens, Merlins, Nolas, Von Schweikerts, Silverlines & more, I can without hesitation say that Sound Labs made the biggest improvement I've heard and compete with many of the current 6 figure $ products out today.
While I agree that amp matching, placement, room size & treatment all must be sympathetic to get great results, I assert that A) It's not that difficult to do and B) It's damn well worth the trouble!
Vs. Maggies, let me tell you that a professional musician friend with a top orchestra owns 20.7s and Rel subs and when he visited he said that the Sound Labs are better. Granted, my other components might be a bit more refined than his, but he is still using high end gear in a room personally tweaked out by Ted of Synergistic Research.
IMHE, Martin Logans only models worthy of consideration are the ones without cone drivers. Even so, I've not been impressed with them vs. other panel speakers. One brand that's good and under the radar is Analysis Audio, especially the Omega model.
One comment about people saying how big all these are. IMHO, if you are focusing a room around your system, panels don't in practice take up any more space or constrict the room any more than properly placed dynamic speakers that prefer placement a few feet into the room. Yes, they are taller, but there are sonic benefits to that and with black or other dark fabric they blend into many rooms and are less visually obtrusive vs. traditional box speakers or many modern dynamic enclosures. Nonetheless, I describe mine as "Mama Bear" sized. My wife calls them "The Twin Towers". With oak frames and matching hardwood floors many visitors tell me that they think they look great in the room, far more than did any of my dynamic speakers.