Last time I died in IB I got 18 kills with it. If u put mostly into stability it's a fast RoF headhunter.

If you dont' have it get it just for the grimoire card. Assuming you run multiple nightfalls every week, what else would use us the coins for?

Works fine in standard crucible. Seems weaker in iron banner

Is Xur selling an exotic weapon you don't have ? If yes, Buy it. There is no reason not to buy it. You will still have a million strange coins by the time the next DLC drops, your inventory will be full of heavy ammo synths on every character and you will literally have nothing else to spend them on. Never pass up on buying a weapon you don't have, even NLB, who knows, maybe it'll get good, like red death, and you'll already have it.