I'm testing, in this days, the Prime 3 and I see that, in the plot feature, there isn't the possibility to equalize the scales between the axes.
I hope this functionality will be insert in the 3.1 version.
Plotting is one of the most important things that, in my case, an engineer have to do; I think the development team must improve this thing, even thinking that you can already do this in MC 15...
Regards