After being away from DJing for a few years, I bought a Mixtrack Pro to get back into it. I bought Virtual DJ Pro, got everything loaded up, and was pretty satisfied for a little bit. That being said, though, I have used the S2/S4 and I can tell you that if you want a more sophisticated 2-deck controller than the Mixtrack Pro, the S2 is it. The components are much higher quality, the effects more functional and expressive, the built-in sound card better sounding, and the overall feel and build quality of the S2 is very high. The Mixtrack Pro, with its cheap plastic construction, doesn't feel nearly as good as the S2 does and lacks a lot of great features that the S2 has. Now, I'm not saying that the cosmetic differences should make a huge difference, but the S2's software and quality are top notch and would most definitely be a huge upgrade for you. And, with the current sale, they're at a price that can't be beat!

Also, after you save up some more cash, the F2 and 2.5 would be a great companion to the S2. For the time being, though, the S2 by itself is a fantastic unit.