I've never seen fs off of these guys. I've only seen a couple gems off of them, but the ones I've seen are worth about 2pp to vendors. I've gotten a ring neck off of one once, but that's pretty much it.
I am a shadowknight and i can run the first 2 floors of unrest with invis on, i went into the bar on the 3rd but have had noting to make me go any higher at this time. With invis undead pulling in unrest is so much nicer, trust me onece you go in with it, you wont go in without after that.