IMO they are the best ribbon tweeters, they just disappear into the music. Since selling my front horn, OB bass and raal tweeter set up I use aurum cantus ribbons and very good they are and reasonably priced. I'm less obsessed these days.
With Raal you get the best customer service available, I fried one when my deqx went wrong and aleksander of raal sent me a new pair of foil assemblies even though he knew it was the fault of another component. A member on another forum had the same experience.