do you have traktor pro already?
if yes, the you have two options.
option 1; get one SCS3d. you can use the input fader as CF or input, or you can make one of the buttons around the outside kill all three freqs. And before anyone decides to chime in, let me say, I DON"T GIVE A RATS ASS whether ya think that's reall scratching or not. SCRATCHING AIN"T SET IN STONE. It's still evolving. There are some scratches the 3d doesn't do well, ie waves, but some it does VERY well, ie scribbles.
the other option, and hopefully this remind everyone that i'm not just some stanton fan who comes here to tout their products. I TRY EVERYTHING! and decide what works and what I like based on the merit of the equipment, giving extra weight to affordability and portabilty. Having said that, I'll do the unthinkable and suggest that you get yourself a DJ Tech VTT 101. It takes 2 seconds to mapp it in Traktor, the deck works very well, and the CF is actually GOOD. It has some curve settings and everything. I have one. I connect a 16 foot usb cable and works just fine.
The scratch /deck/control on both of these is similar. The SCS3D is better, but with the VTT you get a reall life midi CF that will crab OK.