c9 IDE for Salesforce is difficult to manage in a multi-developer org environment.
More than a few times, which is a few times too many for me. We have been working between GIT commits and the synchronisation has overwritten code of developers working in the same org.
It’s too much to expect the dev to only sync a subset of the Apex which they are working on to avoid this happening.
1 org : 1 dev c9 works amazing, however most complex development environments are not setup this way.
Hope this is good feedback