The storage format of BSA is a modified XML, modified for easy reading. But, it has so far been one file which will not scale if multiple persons edit a project as you end up merging a lot on XML in GIT. I am considering moving to a non-XML format, but the major issue here is performance on the XML parser that dissapoints me. Moving to dave each diagram as a seperate file does however have some advantages as this will go better with multiple people editing and using GIT.
This is an issue I need to investigate, but there will be a working GIT integration!