mobico – I heard explicitly from R’ Yisroel Reisman that when Rav Dovid Feinstein was in Aveilus for his father, he Davened Mincha for the Amud at Ahi Ezer prior to giving a Shiur there. While he used his standard ha’avara, he Davened the Nusach of Edot haMizrach in both the quiet Shmoneh Esrei and Chazaras haSha”tz – with the reason being that (a) a Sha”tz is supposed to follow the Minhag haMakom for Nusach, and (b) the quiet Shmoneh Esrei is only a preparation/practice for the Sha”tz’s “main” Shmoneh Esrei – which is the one he says out loud.
an Israeli Yid