[quote=Partisan]
 Yes, following this logic ofcourse, the people outside of the clan that have access to it would likely be in Yukigakure in my opinion - best place to get training for this release as historically most of those people lived there.
[/quote]

Historically, most of them lived in Land Of Waves, which is where Haku came from. Only Ice Release Users we saw were Haku. :3 People in the Naruto Movie used Snow Release, I think they called it.