Has anyone heard the oskar heil line?

I have a vintage pair of ess amt 1b in a second system that
for their age sound great.I have seen the oskar heil line
on this web site before and wondered if anyone had any
experience with them-the heil air-motion transformer has
incredible clarity-detail-sound stage---and they are from
the 70's.
I bought a new pair of ESS amt 1a back in 1975. I had them for 28 years. I had to replace the woofer surrounds a couple of times. They were very enjoyable speakers. They weighed a lot for a "bookshelf" speaker. I wish I would have kept them