So I turned on suds debugging and saw the the F5 was rejecting the save mode "SAVE_FULL". I tried using the save mode of "SAVE_HIGH_LEVEL_CONFIG" and that works just fine. I would post the XML from the debug but I'm having quite the formatting meltdown trying to post the XML snippets.
Here is the output without debugging -
>>> b.System.ConfigSync.save_configuration(filename = '/var/local/ucs/test.ucs',save_flag = 'SAVE_FULL')
Traceback (most recent call last):
....Output omitted......
bigsuds.ServerError: Server raised fault: 'Exception caught in System::urn:iControl:System/ConfigSync::save_configuration()
Common::InvalidArgument
'
I dont know why the F5 would reject the save mode when it is listed in the API documentation.