Yes, I have. I am pleased to report there have been huge changes. I was going to wait another couple of days to post this, but since you asked....
Surprisingly they have changed so much I question as to whether they were ever used. But I know that they were, for many years. The date on one of the woofers is from 2011.
Full story:
I saw these speakers for sale, I wondered what the heck are these? I looked them up, researched them, read everything I could find about them, which honestly wasn’t very much, half of it was from the good people here on Audiogon, and came to the conclusion this might be a good deal, and being a nutty audiophile why not get a second set of decent speakers. I decided to buy them unheard personally but based on the many glowing and positive impressions. I got them home, set them up in my system on Saturday Nov 18 and started playing music. And I listened and thought to myself, this is it? These are these speakers that I have read so many good things about, speakers that have been praised at shows as having "best of show" sound?
I played around with setup, I knew with 8 woofers they had prodigious bass, and was prepared to put them in a different room than this one I have now if it didn’t work. I did hear that huge bass output when placed near the manufacturers suggested position near the front wall so I pulled them well out which tamed the bass, bass was good, but something was off; not right. The treble sounded very laid back, too relaxed, like 40th row in a 40 row theatre. Some tracks sounded like someone threw not sheets, not towels, but sleeping bags over the midrange drivers and tweeters. Well hell, something doesn’t add up. I read these were "musical" speakers, well okay, but this is much flatter than "musical". I have owned Mcintosh amps from the 80’s, which were "musical", meaning the resolution wasn’t great, but something sounds darn right broken here. I checked the mids, I checked the tweeter, yes sound is being emitted from them. Perhaps they were stored outdoors and the tweeters froze to death? I listened for 2 days more swapping some of the cables I have, again playing with positioning, toe out, toe in, thinking they were a little better, I heard some detail that was promising, but still far from adequate, so different from track to track, and scratching my head in puzzlement I seriously did not think they required any major breaking in, but perhaps they would get a little bit better with use? Wondered if anyone else has been through this with a used set of speakers. I then posted this question 2 days later Nov 18.
I then wondered if it was perhaps an amp/speaker mismatch? Maybe these speakers don’t work so well with a solid state amp? So I ordered the amp that most use with these speakers, the amp they were voiced with from the manufacturer and the amp typically used at the shows they were in: a 300b tube amp.
Most answers here were along the lines of what I expected- maybe a little break-in, but not much. Definitely not like a new set. I kept listening and playing them 8-10 hours a day, and some tracks I heard their potential, but most treble still was so inferior to the Magneplanar’s they replaced; at least from 100hz and up- they still however produced wonderful bass below 100hz, and what was output below 40hz was beyond what my maggies can’t even imagine to reproduce. But this was expected. The complete lack of treble, air, and openness was not expected. I thought I made a huge mistake. Maybe the tube amp will correct the issue. Maybe something is broken inside? But there is no crossover to speak of- just a single capacitor.
Well flip ahead to Friday, 6 days later, or about 50-70 hours of playing time, and it was like someone flipped a switch- they are a completely different set of speakers. It wasn’t even gradual, it was like "Bam, here is your treble!" It is now 9 days since I put them in the system and I am now understanding the accolades and best of show reports- they are sounding phenomenal. I have the detail, realistic voices, gobs of pitch and definition but still a relaxed and "musical" presentation they were reported to have. I can’t express enough my delight!
Skeptics: Believe me I considered all other variables- I have a science degree. It was not anything else, I switched back the same cables that were in place on the first day, no other changes were made. And no, psychology and physiology majors it is not an "adjustment period", I am not that weak-minded, and the cold I had and am still getting over? Okay, although I am willing to admit my hearing wasn’t 100%, but hey- my wifes voice didn’t sound overly muffled last week compared to this week- she still sounded the same then as she does now. But the voices from these speakers sure don’t. In the past I have gone through some cable swaps I would admit may be a 1% difference, and I had to go back and forth a dozen times to hear the difference- I would argue the head cold and "adjustment period" are on this level. Whereas the sound I am getting from last week to this week is more like 60% by comparison. Additionally my 25 year old daughter also confirmed this. She was here last Sunday and heard them, then came back yesterday 6 days later and played the same music and agreed it is a night and day difference. "They sound so much more complete". Yes, I now hear the highs to match the lows. 
So yes, to answer my own question these speakers need to be re-broken in. I can’t speak to any other speaker, I don’t know why or how, but these speakers with their Lowther midranges required many hours of playing to sound decent after a lengthy hibernation. Maybe it is just a Lowther "thing". But a few other posters above explained the same experience. Perhaps they will get even better in the next few weeks after the manufacturers suggested 300 hours of break-in for a new pair? They sound pretty damn good now, but who knows!
The speakers are Horning Eufrodites.
