This page, http://www.fossil-scm.org/fossil-v-git/wiki?name=Fossil+vers..., on the fossil-dcm.org site makes the following claim [emphasis mine]:

> Fossil uses a transactional database for local storage, meaning that the repository is protected from corruption even if a crash or power failure occurs in the middle of a commit. Extensive self-checks protect the repository from corruption from bugs. No work has ever been lost due to a software bug in Fossil.

I've never heard that Fossil could eat your data. I don't use it now, but I've tried it for a few personal projects and liked it.