YehudaYona:
There’s a difference between holding on to your mesorah and holding on to a shibush. My “yumtev” illustration from earlier should indicate how absurd this is.
If you listen to Jewish music recordings of ashkenaz kids in England, you will hear their pronunciation of a sh’va as a kamatz. This seems to be a local/dialectical issue, and not that they have a different mesorah than other ashkenazim.
Teimanim, despite the length of their mesorah, have still lived that mesorah in an Arab country. So it’s not unlikely that their mesorah has been, over the years, adapted to the local dialect.
I would guess that this is also how Sefardim (Persians being notable exceptions) came to pronounce both patach and kamatz as a patach. Listen to the languages and dialects of their host countries.
This is why I agree with “Curiosity” that people should not switch to Teimani, since there’s no guarantee that Moshe Rabbeinu spoke that way at Har Sinai, and I would think, in my humble opinion, that he did not speak quite that way, though they may be closest in many, if not all, ways to the original.
Other than some Chassidim and Teimanim, everyone across the spectrum of galus (i.e. German, “Ashkenaz” and Sefard) all pronounce every vowel similarly, if not the same, except for some Ashkenazim who, for some reason, pronounce the cholam as a choylam and many sefardim who pronounce both kamatz and patach as patach.
Since both the “choylam” and Chassidic havara of swapping the vowels and mileil/milra are recent inventions (like “yumtev” or “yuntiff”), why are these not “rolled back” to *their* original and why are succeeding generations being taught questionable, if not mistaken, havaros?