Actually the data on raid0 is not my data but of my users and they knew 
and accepted the risk for raid0. So in my case it should be ok - I don't 
know the importance of the data files which are affected. I just wanted 
to help finding a possible bug and experiment with a broken btrfs 
filesystem before I recreate it.
For my own files I'd prefer raid5 or raid6...

But thanks Duncan for your explanation! Of course there are people out 
there who do not know the difference between different raid levels and 
should be warned!

Best regards,
Alexander