Really? Do you have any pictures? and do you just "know of them" or do you actually know them? Sorry, but there's a lot of BS on the internet.
CAP has had some failures that I think everyone is probably aware of, although, since CAP was bought out by QA1 I suspect that will be a thing of the past.
However, I have NEVER heard of any breakage issues with Magnumforce parts. I've personally seen their control arms (although they have a couple of different designs) and I really don't see how they would fail under anything that could be considered normal conditions.