Dear Rabbi Kornfeld,
(a) In the story of Rabbi Akiva and "gam zu letova", the Gemara
switches language: the Gemara says that a person should say "kol mah
de'ovid Rachmana letav ovid". Then, when Rabbi Akiva draws his
conclusion from what happened to him, he says "kol mah she'osoh HB"H,
hakol letova". Why the change?
(b) Also, is there any significance to the apparent change in the
nusach habracha from "elokai" to "elokai velokei avosai". I'm not sure
how much is intended and how much is girsa.
(a) Good point. It seems that the Gemara's quote of Rebbi Akiva is merely a Hebrew translation of the Aramaic, "Kol Mah d'Avid...." In fact, the Dikdukei Sofrim has a different text of the quote from Rebbi Akiva, in which his statement is all in Aramaic, like the Gemara earlier.
(b) The Dikdukei Sofrim does not have the text of "Hash-m Elokai" at all for the blessing of Ha'Mapil, while it has the text of "Hash-m Elokai v'Elokei Avosai" for the blessing of "sh'Targilenu." It seems that the Ba'alei ha'Gemara relied on the fact that everyone would say the accepted text of the blessing without having to spell it out each time.