ribbons vs domes and sibilance

I don't think you should rule any particular type of tweeter in or out, but your room has a lot to do with the tonal balance. An overly reflective room will sound brighter and accentuate sibilance issues. A well behaved room will make any number of speakers sound good.

OP: Nothing at all wrong with that. :)

I just wanted to point out that marketting hype and audiophiles tend to bias us towards worrying more about the tiniest motor in the speaker.

Some of the most sparkly speakers I’ve heard of late, BTW, were Magicos. B&W’s as well, and I attribute most of that to the choice of Mundorf caps. Go take a listen if you can.

Historically, to get some perspective, the Focal Be and Titanium tweeters had a lot of "sparkle" in them as well.  I always attributed this to a mechanical resonance inherent in them. 

By the way, whether or not a dome tweeter is pistonic in audible frequencies is not a very esoteric question requiring laser diffraction measurements or anything like that. Just look at the distortion plots to compare tweeter A to B and that will tell you most of what you want to know.

I also just want to point out that modern "normal" domes (post 2000) are just sooooooo soo much better than the domes available in the 1980’s. Flat to past 20 kHz, go down to 2kHz? ,no problem!! And ring radiators? Amazing. This argument feels a little as if it were stuck back in the 80’s.

Worth keeping it all in perspective, that some users tweeter’s die and they barely notice it. 😁Why? Most of the music is in the midrange. It’s always fun to talk tech and possibilities of advanced motors, but audiophiles do sometimes get obsessive over the part of the speaker that produces the least sound. Want a really excellent speakers? You want a fantastic midrange.

Also, there’s a new era of Textreme dome tweeters that have come out claiming exceptional resistance to the effects described in the OP’s quote. Will we actually hear it? I have no idea, modern domes are really good already.

PS - Like all other drivers, AMTs come in bad/cheap versions as well, so I don't want to imply that AMTs will always beat out a dome, ring, ribbon.  Implementation matters, both in terms of the individual driver and it's integration into a speaker system.

Like with any driver, implementation matters.  Modern dome tweeters are far far better than described there, and some ribbons are notoriously splashy.  That is, have a lot of distortion which makes them sound extra airy.  Also, not sure how many ribbons out there have wave-guides to begin with, most of the ribbons I can think of do not.  Among the most expensive, RAAL, for instance, I can't remember seeing one wiht a waveguide.

If that's what you are looking for I encourage you to look at the top-end Mundorf capacitors as IMHO they stand out because of this kind of coloration.

Also, a GOOD AMT beats them both for high frequency extension, low distortion, and power handling.  The Beyma horn loaded AMT is particularly interesting for wide dispersion.