I still favor a PAf bid over a PE bid. With PE you kinda need to win quick, because you pretty much neglect Africa and leave Japan in a hole. In my experience PE bid games are most of the time short games, where either the Allies keep Russia, or the Axis takes Russia. Those concepts will happen after 3-4 rounds finishing the game and leaves either the Axis or the Allies fight in a lost position.
The difficulty with a PAf bid of 21 is that you will have 6 inf and 1 arm in Lib. You attack Egypt and in a low luck game you will 5 inf + arm remaining if lady luck favor you. The hard part about this is that the UK will almost suicide with 3 inf, 1 fig and 1 bomb on egypt and with a little luck leave the axis with 1 arm or 1 arm and 1 inf screwing over your whole PAf bid… If you use 2 inf from SEu to fortify Egypt you will have a hard time in Europe and if you put an extra inf in Lib from manch (from the bid) you will have a chance that Russia and England will go for it setting you back a lot…
Its a long time ago I discussed strats for 2nd ed A&A, but still fun.