well, the 850 has no cue buttons, so you’d be pressing keys on your laptop to jump to cues. No gain there. Or are you saying you will use your ipad for remote control for Serato? Or do you mean you are gonna use your SX2 with an iPad app?
Sure you can use the mixer with two CDJ850s, but to add digital capability to it makes no sense once you have an SX2 there. And playing with that setup in pure analogue format is, just imho, offering up so much functionality that I can’t see the gain there either.
You can play with it a bit to find out just how powerful the SX2 is and how obsolete club set-ups are rapidly becoming, provided you don’t live in the “digital DJ-ing is not real DJ-ing” camp obviously. But then, who cares about those guys on these forums, right!
Pioneer gear does (still) hold its resell value, so getting rid of it in favor for something to complement your digital set-up, or pay for your music the next 10 years LOL.
P.s. How do YOU like the Rokits?