I have had GOH open on both phone and computer simultaneously, everything was fine progression-wise. I ran into a different set of problems though it's probably a case of needing to update my video card/driver on my laptop. But both Bluestacks and Memu were absolute disasters for me, in terms of the program freezing up/huge lags in gameplay (Bluestacks) and bombing mid-battle in Arena (Memu). I can't speak firsthand to Nox but my guess is I'll encounter the same problems. If you've got the most updated hardware I imagine it's a different story.