The RAAL 70-10 ribbon is quite robust, capable of handling 150 W. It seems to be intended to work in a 3-way speaker, with a crossover point no lower than 2.8 kHz, using L-R 4th order slopes.
My speakers (Salk Veracity ST speakers with RAAL ribbon tweeter & 6" magnesium alloy W16 woofers) are 2-way and have the RAAL 70-20XR tweeter. RAAL sells them only to speaker manufacturers who sign a non-disclosure agreement. It is probably more robust than the 70-10, but its details are proprietary. We know only that they can be crossed over as low as 1.8 kHz if the crossover is L-R 4th order. There doesn't seem to be another ribbon tweet capable of being crossed over low enough for use in 2-way speakers, unless the mid woofer is small.
Agreed.
For years, I had standard SongTowers with the Hiquphon dome tweeter. In the past year, I replaced them with Veracity ST speakers.
Early on, I was of the opinion that both tweeters were very good and it would be hard to tell the difference. With better quality recordings, the difference between those two could indeed be hard to tell. It's subtle and does depend on the type of music. But I agree with what you say about strings, especially about massed strings in orchestras.
However, I was surprised when I listened to poorly recorded music (Nuggets CDs, one-hit wonders from the mid 1960s). With the SongTowers, they sounded so harsh that I decided they were un-listenable with good speakers. I put them away in an out of the way place.
I had assumed the new Veracity ST speakers, with the metallic mid woofers and the ribbon tweeter, would sound as bad or worse with those recordings. I was surprised to hear that I was wrong. The harshness was much improved, or even gone, and these recordings became listenable again. I'm not sure why this is so, but I was pleasantly surprised.