Ribbon midrange pros and cons


Ribbon tweeters are fairly common on some high end speakers. ...they sound great.....can anyone tell me why ribbon midranges are hardly ever used by some of the best speaker companies. ..what are the pros and cons? 
128x128vinnydabully
Thanks @rauliruegas for that info. I think I’m one of the few planar loudspeaker lovers who never heard a pair of Apogees. For some reason they didn’t seem to be big on the West Coast; I never saw a pair in any California hi-fi shop, Northern or Southern.
@larry5729

Those are AMTs not ribbons.

@vinnydabully

The BG Neo planar midranges are real good, Philharmonic uses the Neo 8 in their tower speaker. http://www.philharmonicaudio.com/phil3.html

I also saw it being used in a speaker when I went to the Florida Audio Expo.

No clue on distortion, but it’s imaging/soundstage is excellent for the price, very glad that PS Audio is considering them, it looks like they are using the Fountek NeoCD3 for their tweeters, which is also a good choice, obviously not as good as say a RAAL 70-10D, but it is of course around 1/5 the price.

EDIT: Going off this image, it looks like the tower is using this Dayton tweeter, which is still efficient and has good imaging/soundstage, but I guess/hope it’s a placeholder and not the final choice, as it would be odd to use a different tweeter for the bookshelf and tower (you an see the bookshelf in the background with the Fountek tweeter). I also can only see the bookshelf woofer as being a KRK or HiVi one, as hardly anyone is making yellow woofers and I doubt Paul requested for the cone to be yellow.
I live just 40 miles from where Apogee was.
I suspect they were not prevalent on the west coast because they were very expensive to ship and very fragile which would have added a lot to the cost.
Scintillas destroyed more amplifiers than any other speaker I know of which interestingly enough made them a very popular cult item. They were ok but not near as sonically correct as the Divas. If you did not listen above 95 dB the Divas were fabulous. Their real talent was in the mid bass region. Upright acoustic basses were unbelievably real on these speakers. Only electrostats are capable of that kind of realism. Magnepans come very close. 
All planar dipole speakers have significant acoustic advantages over drivers in a box. The only place they stumble is in the very low bass. A subwoofer array fixes that,
May have much to do with production costs and logistics for the mass market. Being an Apogee owner (Duetta Signature and Scintilla models) there is a reason (in earlier post)  why someone drove from Indiana to NY to get them. Yes they can be challenging to set up, yes they are obtrusive to some and yes the Scintilla’s are tough to drive. Once set up correctly they are quite remarkable top to bottom without subs, IMO. And just to strike some balance i do enjoy my old LaScala’s and my buddy’s Golden Ear Triton reference speakers. So many great and unique choices. But they are no Apogee...:). 

With the DSP sub/servo stuff today it will be interesting to hear how the new PS Audio AN’s sound with midrange ribbons. I am sure a great outcome.