Elac 4 pi Plus.2 supertweeters...

I'm wondering what observations other Elac 4Pi Plus.2 owners have about these supertweeters. I have a pair, put them on my sweetie's speakers (Sound Dynamics RTS 3s) and they sound terrific. He's an opera singer, and a pianist and he noticed the improvement over the droopy highs of the RTS 3s immediately.
I like them very much, but his room's not great. I've also heard them with my Alon Viper Plus speakers, with good (not fabulous, just good) results. I'm wondering about the experiences of others. I did notice the other day, when I played a Nina Simone cd that I expected to sound bright and awful, that her "Ne Me Quitte Pas" cut was extremely moving, more so than in my systerm WITHOUT the Elacs.
What say you guys???
I also would be interested in any comments on this supertweeter. Does anyone have any experience with it?
I own a pair of the early version of these and they work wonderfully with my Tannoy speakers. I have tried them on some other speakers and they don't always work as well. This is definitely a try before you buy product.
I have a pair I've added to my Piega C8 Ltd speakers (which already have ribbon tweeters/midrange) and they have made them sound even better! The omnidirectional quality of them adds to the spaciousness/depth - I won't ever sell them!
I recently added a pair of these supertweeters on my Nola Viper Reference and the result are fabulous. An article in the magazine Hifi+ has precisely commented the Elac 4PiPlus.2. Here is an excerpt which I found very near from what I feel :
"Transparency and image placement were both improved, while the tonality and harmonics of mid and high-frequencies were both significantly better.
Percussion detail was more natural, the nature of the instrument more apparent. But it was the texture and tonality in the lower-mid and bass that really impressed, with much greater definition and detail readily apparent. Dynamic speed, precision and substance were all improved along with the shape and duration of individual notes, making dynamic contrasts more emphatic and musically effective. This increase in presence extended across the entire range, brass in particular gaining body and a satisfyingly realistic rip to its tone. Overall timing was also improved with musical phrasing making more sense. [...] This Elac super-tweter extends the performance available from existing speaker systems in a significant and musically imporlant way. High-frequency extension is no optional tweak - it's a musical necessity, making your system more natural and more naturally communicative."
Anybody tell me where you can buy them at a REASONABLE price - am not about to fork out 3000+ bucks on a pair!
I am using a Elac 4pi for over 25 years now, and had not even a single problem with them! So replacing the ribbon seems not be an issue.
It has a specific character, best described by Jannweiss above. It find it overall extremely musical and engaging.
Has anyone experienced phase cancellation issues with theirs? I have been using the 4PI Plus.2 for a few years with my JM Lab Electra 905s. The 4PIs are connected to the speaker terminals and set atop each speaker cabinet. I have noticed that when the 4PIs are disconnected, certain frequencies become more articulate; likely due to phase cancellations. This seems to be unresolvable due to its top of cabinet placements and  the small wavelengths of super tweeters.  I am curious if anyone else has experienced this problem and if so, were they able to find a solution?  I like the air that the 4PIs bring to the soundstage, though I am bothered by the loss of musical detail sacrificed in other frequencies.