Taalmid lo Chacham,
The question on the Beis Ephraim is that if the Mas’e of zKum Rabah V’Shochtei L”rav Zeira was brought down to disprove the chiyuv of Ad Di Lo Yodah then why would is it the story ends off that the following year Rav Zeira stated he would not have the seuda with Rabah because of “lav Kol Yomah Israchish Nisah” he would not have needed a Nes since based upon the previos years events there was no lomger a chiyuv to Drink.
The Stiras in Rav Akiva Eiger you quoted could be ansewered simply that the mitzva on Purim is not neccassarily to get drink rather it is to get drunk hence Rav Akiva Eiger question if it is not a mitzva to Drink (i.e Simcha) then why only wine anythige that brings about shikrus should be used.
As an asided the Rambam seems to hold there is no chiyuv to get drunk at all rather the Gemora is saying that when one gets drunk they are potur from Drinking further.
I would add that There is a well known Senior Rosh Yeshiva who refused sign the letter against drinking beer on Purim because he stated that when he was a bochur the minhag in Yeshivos was that you can fulfill the mitzva with anything that gets one drunk and he is not big enough to sign against a minhag.
Howevr I do know that Rav Shmuel Berenbaum zt’l held that since beer is dangerous one should only drink wine.