Questions about decorator crab?!?!

[reefnooby]

Hey guys! So I saw this guy at my lfs, and i thought i was just the coolest thing. The fact that it can use live growing coral as camouflage blew my mind! Anyways, hes been in the 55 for about a week with only 10 small hermits 3 nassarius snails, and an emerald crab as my CUC for now. I have looked this guy up quite a bit and people are saying that it aggressive towards fish/inverts/corals. I was wondering if my crab behavior was normal because i hear they hide most of the time which is the exact opposite of mine.l. It doesn't move much, at least when i'm looking, but its in a different spot every time i turn on the lights. It is always perched at the highest point in the tank right under the lights, and he DOES NOT MOVE. or even wiggle from the current. Even when snails and my crabs crawl on him he wont nudge them off or anything. Its real bizarre but very cool to watch. Also it has not ripped up my kenya tree or GSP's yet. I believe its a Spider Decorater Crab. Is it normal for them to perched way up there when lights are on and why do they have such a bad rep?