considering that you already can make an attack as a standard action that ignores the minus to hit from range, automatically threatens a critical, is a sneak attack, and the sneak attack can be multiplied if the critical is confirmed (not to mention they can wait in the woods until their chance of confirming the critical is 19/20 (fumbles) because focused shot has no limit.)
I think each ability alone would be underpowered, but together I'd say it doesn't need anything additional.