Well, imps become more and more dangerous when you have more melee monsters to deal with and it becomes difficult or impossible to shoot them, as they are constantly draining you hp while you can do nothing about it before you kill the monsters in you way. This becomes more serious at later levels when you have more melee enemies and more imps. Also, when you're on low hp's, you can't see them while they shoot at you. And yes, I hate 'em.
Also, could the game show what night is going currently, things go pretty fast while viewing record files and I'm not always sure what night it is.