Yeah, I turned off all the tier 4 enemies. The black imps are dumb. Actually I turned off most of the new enemies except the zombie variants, and turned off most of the weapons I never use, like the standard pistol. Did you try the hell on earth map pack for brutal doom? It's pretty cool.
Autoshotgun makes the dark imps go from annoying as fuck to glass cannons, quite efficiently.
Speaking of which, I'm working on another Doom mod idea of late...