Traktor Scratch Pro wont work with any soundcard that is not “scratch certified” the RMX is not certified so you will not be able to use timecodes through it… You could use Virtual DJ Pro and that would not be a problem, to upgrade from the RMX serial it is only $150 which will also entitle you to VDJ8 when it’s released and unless Native Instruments really pull something out of the bag for version 3 or serato open up their platform VDJ8 will be better than both of them in terms of functionality.
If you are wanting to use VDJ it’s a good deal as if you try to sell the stanton gear you would get about the same money back as a RMX, and using real controls is always going to be better than touch ones imho.