well before you get a cr-10 have a look at the qidi: https://www.amazon.com/TECHNOLOGY-3D...idi+3d+printer

Basically a flashforge pro, just cheaper - and given the millions of hours these printers have printed abs all over the world - it's not an issue.
Well 3d printed abs has a lot of issues and I wouldn't personally bother with it - but mechanically there's no problem.

That said trakyan is right - dual extruders sound cool - but in reality they are a real pita.
What you actually want is either a machine with independant dual extruders - like the bnc3d sigma, OR a machine with two feeds into one printing nozzle. Which you could probably add to a cr-10 fairly easily.