Without justifying switching between Sephardic and Ashkenazic
pronunciations the idea that the Sepharadic pronunciation is closer to the
original is not (just) some Zionist plot. R' Yakov Dovid ben Zev Vilovsky
Z"l the av bet din (head of the court) of Slutzk and later rav of Tzfat
(and author of commentary on the Yerushalmi (Jerusalem Talmud) as well as
other works) writes in his responsa (Bet Ridbaz- recently republished by
Mosad Harav Kook) that it appears that the pronunciation of Loshon Hakodesh
by the sepharadim is more correct than by the ashkenazim because of the
many wanderings and great suffering that the ashkenazim experienced. (Bet
Ridbaz end of siman 27- appears in parenthesis).
In addition logically it would appear that the Teimani pronunciations are
closest to the original, being that the Teimanim differentiate between the
pronunciation of every letter (no two alike). In the Teimani pronunciation
there is a different pronunciation for "vet" and "vav", "koof" and "kaf"
etc. In the modern sephardic and ashkenazic pronunciation there are
redundancies of phonetic sounds.
Again, this does not justify altering ones masoret(tradition).
Tzvi