I just wrote another post on a similar subject. Hope you don't mind me posting the link. https://forums.macrumors.com/threads/1494936/
I've been playing around with this Elementary Os - OSX Look Alike and I'm pretty impressed with how fast it is on my girlfriends little Aspire ONE netbook.
The drawback on any Linux Distribution is the professional application availability. If Adobe would jump on board I would seriously consider it.
I saw this, actually one of my friends said this is what he was going to use. For me it lacks a consistent UI (Not a fan of the big color icons) and apps like Pixelmator I couldn't live with out.