With Lenny loose a lot of players already stay out of C2 at night, add more random killers, unanounced, and more players will just stay out of C2, making C1 more crowded and laggy.
I like the general idea, but do it either like a regular anounced invasion or make them like regular mobs so mm still works for those who don't wan't to play the game that way.
Bat17