I really like [name]Milo[/name] as a girl. But I wouldn’t spell the name that way. I wouldn’t know how to pronounce it. Stay with a [name]Milo[/name] or Mylo spelling. I love the name, go for it. 
In my opinion, I think that the Myleaux/Shyleaux spelling is just too “out there” unless you live in [name]France[/name]. Nobody will guess that spelling- they will hear [name]Milo[/name], not Myleaux. However, one thing I like about the spelling Shyleaux is the nn Shy.
I love the name [name]Milo[/name] for a boy only. Spelling it Myleaux doesn’t make it girly. It makes it a spelling nightmare.
…Yet another agreer about Myleaux being odd, but I have a suggestion - Margaux. (pronounced MAR-go) It’s more accepted, as far as I can tell. My sister knew a Margaux. It could also be spelled Margot, to be German. If you are set on Milo, sticking with Milo or Mylo will make roll call a bit easier on your daughter every September.