After making a switch from Serato to Traktor, I've decided to upgrade from an SL2 to an A10. The only down side to me is that it requires a power supply, unlike the Serato audio boxes which can work solely via USB. Aside from that, it's definitely worth picking up, generally I find the audio quality much better than Serato's. Along with that, pricing. An SL4 would cost significantly more than an A10 and the A10 essentially does more than the SL4 has to offer.