“sbeph
Oh by the way Reb chaim kanievski paskens that technically if one misses the beginning of chozres Hashatz there is no inyan to listen to the rest. AND saying Amein w/o kevanah is a real averia is for sure worse then learning and not saying amein at all. “
And R Chaim also says that a person learning during C”H not only does not get schar for learning but is doing an avierah
still see REMA MePano that the MB quotes “NOT to REBUKE anyone who learns” who says in the full teshuvah “since he he doing 2 mitzvohs at the same time”…..