For durability, I can not say much, we have only recently begun. The general opinion of the kinship is allerdins "regardless of whether cheap or expensive, that are all the same fast break".
To fit: Yes, they are quite small, but still fit the rather broad feet of my children. However, I made the "mistake" to heed the advice of Vorrezensenten and have a number of purchases greater the ballet slippers. This number they are now too big and are on the front. Until now, however, seems to be a problem when running and race. If necessary, I can suggest you order one size smaller also again. The other way round would have been stupid.
The only criticism: the sizing charts could be preprinted. I have the shoe size now purely written with permanent marker, so I do not confuse the shoes. But that seems to hold not very good ...