Dear Rabbi, are ktav Ari sifrei Torah, tefillin and mezuzot not lechatchilah to use for non-Chassidim? And does ktav Beit Yosef invalidate ktav Ari? And vice-versa? Do you know if Rav Kook ever dealt with this? Thank you very much for you time and help.
Rav Kook [in Orach Mishpat 8] writes it is Lechatchila to follow ones family tradition regarding the Ktav of Tefilin, however Bediavad can fulfill his obligation by wearing the other Ktav. Similarly a mixture of Sephardi and Ashkenazi writing does not invalidate the Tefilin [ibid 7] Rav kook refers to Askenaz and Sephard how much more so to Ar"i and Beit Yosef that have only minor differences.