For what it's worth, Sir Big Mac Davis has a pretty good strategy for getting 100% kills in this level - starting at 7:41 he lures all the barons and specters to the bars near the red key, and uses infighting and the splash damage from the small amount of rockets you get to take them all out efficiently.
And since we on the subjects of E4M1 and punching things, I wanna once again call out my Doom Challenge, the "NIN Death Box" - I wanna see someone stay inside that thing and take on the four barons with what they've got (most likely coming down to fisticuffs). It always seemed to me that was the proper way to do it, instead of running out like a wimp and sniping them from afar, and I just wanna witness it, even if it's tool-assisted.
And speaking of punching barons, shout out to this guy, because he's cool.