I must thank you for putting this together. I really never use these sort of mods for too long before ditching them.
After playing through Plutonia Revisited with Expanded, I found this mod to be a real treat, and I consider adding it to my Global Autoloads. The extra gore is satisfying but doesn't affect/change/molest gameplay nowhere near as much as Brutal Doom, which I am grateful for. The fire graphics are just incredible, and have a great synergy with GZDoom 1.70's improved light shaders.
I quite liked the use of PSX sounds for the monsters, it allows them a good bit more of personality rather than having than having a static pain state sound for most of them. Infighting affairs happen to have bit more of a personal touch to them. Just listen to how that cacodemon whimpers as a revenant lands each subsequent blow. The use of 'hi-def' Doom SFX along with Doom 3 SFX works well and doesn't end up as cartoony as Beautiful Doom.
As good as it already it is, I'd like to suggest a few improvements:
When fighting numerous demons at once in large areas, I like to know what's coming my way, every second, so I can fully understand the situation, who I'm fighting and rationalize my next move. When excited imps, mancubi and revenants are flinging death in my general direction, I find myself often getting them mixed up, as they don't stand out far enough from each other, besides size and other subtle details. Differentiating between the three helps one get an idea of monster placement, and how many there of them.
IMO, I think the imp fireballs should stay as they are. For mancubi, their fireballs could be modified to have that intimidating "meteor" look, as they did in Doom 64. Perhaps the center of their fireballs could be darkened quite a bit to look like there is some serious mass within that fireball, rather than just a supersized imp-fireball.
Revenant missiles, are the easiest to get mixed up with the imps. With their heightened danger factor, they should be instantly recognizable from everything else. Rather than looking like an overheated, flaming rock, they should resemble such as in Doom II: a flaming missile.
IMO, use the PSX SFX for the rocket launcher, its much more badass and would work great for this.
With the new torch effects, perhaps the candle could be edited to have its own cute little flame as well?