I dont know the official word on this but I dont think the SB unit is supported in recordbox (feature level to low maybe) , I know my SB2 is not yet supported ( i have not tried the new beta yet).
I do know that the latest Traktor, serato and Virtual DJ do support it with the latter requiring a free midi map to work as it should, the default VDJ map is not right in my opinion.
I personally recommend Virtual DJ, mainly because of cheap cost, years of using it I have found it to be very solid software, however serato & traktor do have a little bit better audio latency on older hardware.
Any serato/traktor users wishing to input their advice are welcome,