DDJ-SX or CDJ's?

I'm currently only using my cdj2000's to control mp3s on a hard drive or sometimes rekordbox on my laptop. I no longer use CDs and was considering getting this controller to replace my cdj's and djm 800. What do you guys think? Is it a decent bit of kit? Can I add effects to the other channels (my 1210's) and is it only serato it works with or can it work with my hard drive/rekordbox or other software?