Collector into IE is my current build but I've been thinking "what's the point in collector" I like the raw stats the passive is probably useless. I wish it tracked kills throughout the game so I could evaluate it.
Collector really just delays ie. Maybe ie then essences rever is better.
Collector early is better than late for a few reasons. Lethality decreases in value as the game progresses and 1hp escapes have more value as kills earlier in the game.