I like Magnus. Wouldn't bother me. But I am open to most names that aren't entirely made up. I much prefer these kinds of names to names that have a weird version of a traditional name.
Oh, and to OP, I would go for it if you love it, but I clearly don't care whether people think my DS's name is "too ethnic."
People scrunched up their noses when I was deciding between Sebastian & Felix bc paired w my last name, "people would know right away that he's Hispanic!!" Um. He is half Puerto Rican... I didn't realize I was trying to hide that? I could have named him James and our last name would give it away.
And yet we are the farthest away from Hispanic and Felix was on our list!!!