I have them in use since they were released and I don’t think that I’m particularly gentle with them. So far I got no indication of any plastic weaknesses, though. I’m using the black model, just in case that matters. BUT there has been at least one report that I could find on the forum, a black one in that case:
Some time ago I had some pretty cheap ones where the plastic band broke in a similar fashion to what you’re describing - suffice to say that it was not easy to fix in that case. So I think I generally do have the potential to break them. 