2) They're not that higher in quality. The game has very little trouble rendering 1000 tris models.
3) The huanman isn't meant to be a super dangerous enemy. But its projectile is still fast, has homing qualities and boomerangs like the demon's fireball. They can still hit you if you're not careful. And the big one's projectile has a large hitbox. Though that one was more to make it easier to dodge their devastating melee attacks.
5) All I did with the albino is slow down their projectiles. Previously it was very difficult to deal with them in a larger fight. It still does 20 damage (which is 40 on serious) and the albino still has a lot of health. So I wouldn't say they're equal to reptiloids.
6) The Lazobar is essentially a lighter weight reptiloid. Do keep in mind, its projectiles are potentially eternal. If you don't take care of them quickly enough, they can really flood the battlefield. Sure, when you focus on them they're pretty easy to deal with, but once there are other enemies, they can easily sneak in a few hits.
7) I think the firecracker is still tougher than the rocketman. They shoot multiple projectiles. Sure they're easy to dodge, but when there are multiple of them, that can be difficult. But of course, the beheadeds are meant to be low tier cannon fodder. Still, the mod does increase their movement speed and attack distance, so they are ever so slightly less useless.
8) I wouldn't say they're less dangerous. It's the projectiles that make biomechs dangerous after all. That said, the reaction speed reduction might be a bit excessive.
