Snap Shot def. increases you accuracy.
For example in station when killing a person at the number 5 hack spot from the 'tower/walkway' near the number 4 hack spot it would only take me half a clip with SS, whilst i need a whole clip without SS.In open maps like outpost it allows me to kill opponents far away with lesser bullets than without SS (and thus faster)imo it is basically good for far away ADS kills. As for Hip-firing, honestly aside from with sniper loadouts it doesn't help me much there, and so for hipfiring with my CCP i find SS not necessary.There is no noticeable difference imo when hipfiring with or without SS. Mind you i barely hipfire at faraway targets. Against good opponents with WiiMote i know that winning a faraway gunbattle is against my favour so i try to limit the range as much as possible between me and my opponents.
I have to admit though, i barely slap on SS. I prefer Bio Booster. Noobish as that may be.