LU: I am currently learning with the Dirshu Mishna Berurah and he quotes the Igros Moshe extensively. However, Rabbi Hoffman in his article quotes on the issue of Vsein Tal Umatar “Unless you are a talmid of Rav Moshe, most people follow the Mishna Brurah.”
This is not the only place where “hamon am” does not follow R’ Moshe. One of the other places is the haftorah for Shabbos Shuva where R’ Moshe writes that one only should say the Haftorah from Hoshea and not add on from the other neviim as most kehillos do.