Bacula is actively developed. http://www.bacula.org/git/cgit.cgi/bacula/log/?h=Branch-7.0 No risk of being unmaintained at some point, since they build commercial stuff on top of community Bacula.
It is better at several large files than thousands of small files. In fact when you throw millions of small files at it it chokes pretty bad (CPU skyrockets). So if you need to backup an SQL server data store you'll be just fine, but thousands of XML files? Maybe not.
Regarding the small files performance - thanks for pointing it out. We are using Bacula to backup JIRA & Confluence data stored directly on the disk as files. Some customers have thousands of small attachments in their instances. I haven't seen any performance problems though. Maybe because not only there need to be thousands of small files, but also they need to change often, which is not a case for us. Will keep this in mind. Thanks.