Hello Reb Mordechai
We mentioned in the shiur about Abba Shaul's version of the Avodah on Yom Kippur, and I notice Rabbenu Chidah in Yosef Ometz (Siman 51) writes that one should avoid the Abaye nusach on Yom Kippur as we don't take on like this and we say the other opinion during the Avodah, like the Chachamim.
Have you seen any discussion regarding this issue ?
YCD COHEN (PRESTWICH)
The Rambam in Temidim u'Musafim (6:3) rules like Rabanan of Aba Shaul as does the Smag. However, the Perisha (OC 48:2) states that Rashi holds like Aba Shaul as does the Tur (OC 48). I imagine that the Chida was prefering the Rambam over Rashi. Atah Konantah (the Nusach of Avodah generally considered to be the most accurate and recited by Nusach Sefard) holds like Rabanan. Amitz Koach (the Nusach said by most Nusach Ashkenaz Kehilos) is less clear but would seem to hold like Abaye's Peshat on Yoma 15 and rule like the Rabanan as well. This is, however a bit problematic, since the Tur rules like Aba Shaul and we say Aba Shaul's Shitah every day before Shacharis.
The Likutei Halachos (Yoma 11b) points out that in fact one is Yotsei whichever Nusach one says. For further information see Avodas Yisrael (3-4).