Based on a quick look at NiFi, SQL Server Integration Services (SSIS) seems similar. The configuration management tooling for SSIS is pretty good and it's amenable to version control better than, it sounds like, NiFi is. SSIS still suffers from the potential "gotchas" the top-level poster mentions.
I haven't used SSIS since about SQL2008 - back then it terrible to use with version control - not only was it a huge blob of XML, it had more xml escaped and shoved into attributes of the main document! Whats more it seemed to re-allocate the GUIDs of the elements every time you opened a diagram, so there were always changes...
