Q. Shalom, Someone with background in Ashkenazi and Sephardi communities, and is able to daven with either pronunciation.
He always davens with Ashkenazi pronunciation. Can he daven for the omud in a Sephardi shul with Sephardi pronunciation, or avoid davening for the omud?
Is it same the other way around (someone that always davens with Sephardi pronunciation, daven for the omud in Ashkenazi shul)?
The question is about pronunciation, not Nusach.
Thank you

A. In regards to the reading of the Torah especially in regards to Parshas Zachor, there are various opinions if one can comply when reading or listening to another different pronunciation than one’s own.
(See a collection of different rulings on Ribavos Efraim O.H. 6: 376 and others).
In regards to tefila, Horav Shlomo Miller’s Shlit’a opinion is to follow the many Poskim that maintain that if one davens before the omud, he should follow the established pronunciation accustomed in that congregation, even when different to one’s own and he would still comply with his obligation. (See similar in Yalkut Yosef – Tefila 105: 5, Igrois Moshe O.H. 4: 23 and 65, Minchas Yitzchok 3: 9, Oz Nidberu 3: 48, et. al.)

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a