Mayan: I don’t have my own opinion on what ad d’lo yada means. All I know is that most poskim have either rejected ad d’lo yada or understood it as meaning something other than complete stupor. I don’t know if it’s fair to say that the face value of ad d’lo yada is that you’re not yotzei till you’re drunk out of your mind. There are different opinions on what the poshut pshat is here. A number of rishonim understand the simple meaning of the statement as saying that ad d’lo yada is the limit at which a person should drink no more, rather than the goal that needs to be reached. The Rambam, as understood by some achronim, holds that there is no shiur for how much one should drink or for how drunk one should get. There is simply an obligation to engage in drinking. If a person happens to reach the point of ad d’lo yada, such as if they pass out or otherwise achieve the status of a shoteh, they are obviously no longer mechuyav b’mitzvos hayom. This fits quite well with the simple mashma’us of the gemara.
The predominant p’sak in practical terms is to simply drink yoseir milimudo.
The Beis Haleivi wrote that people should only get drunk if they are doing it lishma. Many recent poskim have stressed the fact that people should only get drunk if they know that won’t behave in a dangerous or assur manner. (That includes bentching or davening while drunk, which is assur). The purim seuda should be a tikkun for the seuda of Achashveirosh, not, chalilah, lehefech.
My RY holds of yoseir milimudo. Personally, I usually have a little more than one bottle of wine during the seuda. That’s more than the arba kosos I have on Pesach, which is the only other time I drink, so I think that I am yotzei “yoseir milimudo.” I can easily recite poems and calculate gematriyos afterward, so I suppose I’m not yotzei Tosfos or the Be’er Hagolah. :