I'm looking to learn about Air Motion Transformer technology

Eric...you need to rethink that emphasis on those 3 octaves to also include the CRITICAL harmonics....see the imperfect amp thread..but ya, there are some AMT that are listenable, and antime the ATM is puking out cash, I am all ears...dyslexia or not...

also there is a decent wiki on AMT w links to the 8 patents...and ESS appears ro still manufacture the tweters in various sizes and complete speakers, might be a fun winter project...

A lot depends on the quality of the AMT ,in the Wharfe Dale 
maybe $50 each  top AMT can go over $400 each the bigger ones 
operate from the midrange to high frequency , I have had Dayton $70 AMT that were ok but lacked refinement, I have a Monitor audio Studio , which took a lot of technologies from its $25k flagship and its very refined and reasonably priced under $2k 
since I rebuild the Xover even in speakers over $14k many times it is the weak link using cheap Xover parts  just to save money .
80%  of speakers under $10k use what I consider at best average grade a Xover parts. Since it is the heart of your Loudspeakers 
everything goes through there are greatly determines the detail and refinement you get. I had the owner of Harbeth hang up on me 
when I questioned him on a $4k speakers using $3 Taiwan capacitors, being in the U.K. another $100 and using local Clarity capacitors would gain much more realism that is just one example 
even the $80k Martin logan using under $10 capacitors , I called them on it ,when spending good money like that you should get the top Of the line brand they choose to use. Makes no sense to me have some pride ,to me I would rather pay a little more for higher quality ,or just upgrade the Xover  .

Spatial is using them in the new X3/X5:
http://www.spatialaudio.us/pagex3

Heil speakers used the AMT ribbon tweeters in their speakers back in the early seventies, if I’m remembering correctly. Those were the first AMT tweeters I’d ever heard of. They were ESS made I believe. You can still find them for sale on Ebay. They were German made (hence the Heil name of the inventor) so I seriously doubt they had any cheap Chinese plastics in them.

Mike