Thank you everyone for their replies...of course, she is learning both styles, but I personally think she should perform with the rond de jamb, just because it looks more tidy and less sloppy.! I think most of you agree, I just wanted an international view on this regard, like if people would rather see one or the other.
And yes arms are very important!
Also, I think the prettiest fouettes are the ones the ballerina manages to stay on the same spot (sur la place) it makes it even more impressive!
Anyways I gotta say, from the Russian the worst I saw so far is Alina Somova