Personally, I don't see a down side to focus fire on bullet hose autos, I usually prefer the slower rate of fire autos as the recoil is more controllable making it easier to place headshots and they generally have better base range and damage. With focused fire it slows a rate of fire just slightly but it makes quite the difference, plus you deal extra damage which is always a good bonus. If you can get a bullet hose with focused fire and a range buff (preferably rangefinder because when you aim down sights it will literally transform into a different gun and you'll have basically two fire modes: controlled long range and spraying up close) I'd recommend it, however that is just my opinion. When I get a new gun or get a gun with an interesting set of perks I go and patrol the moon. The starting area for the moon patrol is basically a long gun range, then there's the inside bits for close range, I find it perfect for testing out all sorts of different weapons. Maybe try it out, then you'll get a personal feel for it and be able to make a better judgement for yourself.