[Captain Galus]

Once I found out that they require line of sight (a looooooong time ago) I immediately lost interest. One HKM is worth a Storm Bolter on a Rhino or a Sergeant, both of which can and do kill more models than a single HKM.

I can see why IG take them, though. If I was an IG player I'd probably put on on every vehicle in my army.