Im gona have to talk here, The s4 isn't really made for beat matching (e.g. the tiny faders and the position of the jog wheels) Personally, I don't mind if they use it, as long as they CAN beatmatch normally, it doesn't matter to me. GTFO, just get out if you even consider using the sync button then you are not a DJ, if you use sync you might as well be running nightlife... if its hard to beatmatch on then maybe it shouldnt be a DJ controller If you do sync it gives you more time and freedom to be creative with effects and morphing the track etc. I'd say a fair few people sync these days anyway