I'll admit, I am not in love with making Magneto a hero. The idea in and of itself is not bad. I just don't know that it's compelling enough to effectively render a villain of Magneto's stature redundant. One "Xavier" (whoever that might be) advocating for mutant/human coexistence ought to be enough.

Now if you were to posit that Xavier dying turned (or kept) Magneto good, à la Age of Apocalypse, that's something I could fuck with.