I wouldn't say splitting fire is OP. But the fact that grey hunters are better then tactical marines as they have 2 close combat weapons and counter attack for less then a tactical squad is something i don't understand in the slightest. It makes taking Blood Claws pointless and also doesn't make sense points wise. Also you can get 2 weapons like a melta or plasma gun for free when you have 10. Compared to the tactical squad with a free missile launcher and flamer, i know which one id rather take, especially with grey hunters being 20 points cheaper.