Best Morel tweeter I know is a version from Intertechnik Germany in the same outline than this under
https://www.morelhifi.com/wp-content/uploads/2019/12/ST1308.pdf
but without ferrofluid.
I don't know about the version under
https://www.morelhifi.com/wp-content/uploads/2020/01/CAT378.pdf
because no Thiele Small Parameter (especially Qms) are published (Qms value without ferrofluid much more higher).
Disadvantage of both are too low spl - that means unwanted power compression already at mediocre spl values (like usual of most typical dome tweeters for home audio application).
check out this threads:
https://www.diyaudio.com/community/...ter-without-titanium-and-without-horn.155885/
https://www.diyaudio.com/community/...nklang-phenol-99db-based-to-rcf-tw116.155882/
https://www.diyaudio.com/community/...er-overview-without-ferrofluid-wanted.161577/
please note - there are a lot of dead links - in this case copy the link in this portal:
https://web.archive.org
P.S.: From my impressions hard domes are not harsh in cases of coated metal, kevlar (e. g. Audax TW074, Focal inverted dome T120TDX and T120K) and phenol (Electro Voice T35/T350)..
Except there are no equalizing in the crossover network integrated.
Uncoated metal (titan beryllium etc) and ceramic from my view always harsh and crispy even, if there are equalizer networks integrated.