Hello,
I just came across the Ask the Rabbi section of Yeshiva.org @
http://www.yeshiva.org.il/ask/eng/ and this very question about nusach came up... Here are three of the relevant answers:
http://www.yeshiva.org.il/ask/eng/?cat=297
Question:
I am Halachically considered Sefardic because my father is Sefardic (although my mother is not). I grew up in Ashkenazic schools and always davened Ashkenazic. Yet for Rosh Hashana (and sometimes Yom Kippur) my family goes away to a Sefardic shul and I daven in the Sefardic nussach. Is this proper to switch back and forth?
Answer:
It is very important that one should say prayers one is used to. Therefore, switching Nusach is not advisable. You should try to daven regularly with your Nusach, unless the davening is completely different in which case you can switch.
Rabbi Yitzchak Grinblat
Question:
I have always prayed nossach ’sfard’ but I have been living in London for 4 years now and in most of the places they pray nossach ’askenaz’ for now I plan to stay here. I am reluctant to switch to nossach ’askenaz’ as tradition is important to me on the other hand it does not make sense to pray in the different nossach than everybody. Should I switch? Thanks
Answer:
It is of great importance you keep your Nussach. The Jewish nation has survived generations by keeping family traditions. Therefore, when praying you should use your Nussach, unless you are a Chazzan or answering communal prayers such as Kedusha or Tahcanun.
Rabbi Yosef Weitzen
Question:
Before I became observant I davened in a non orthodox shul and davened Nusach Ashkenaz. For the past few years I have been going to a Chabad shul and have davened Nusach Ari. I now realize that Chabad is not for me. Can I switch back to Nusach Ashkenaz with or without a Hatarat Nedarim?
Answer:
The answer is complicated. As a rule, if by your father's or grandfather's the Nusach was Ashkenaz while davening, there is no doubt you can daven Nusach Ashkeanz.
If they used to daven Sfarad (Chassidic), it is better you continue davening in that Nusach. In any case if you daven in a shul that is Nusach Ashkenaz, you may continue davening Ashkenaz.
If your shul is Sfarad, and your family custom is Sfarad, and you want to switch to Ashkenaz, you should do Hatarat Nedarim.
Rabbi Eliezer Melamed