I use export/import functionality to sync Pc/Mac/ipad/iphone data using a custom procedure.
Each client export data to a sync file, which is stored in a common path.
Main office import and check all data, then releases an updated version of the app.
This process was refined over time and now it works pretty well.
The only issue that happens is that during import sessions (multiple files are processed) sometimes I'm required to insert password for one of the files and I really can't explain why.
This is a problem because all files are protected by admin password and I do not share it, so I always need to supervise import process to provide password in the case it's required