I just gave this a try and I think there's a potentially worrisome problem, it silently failed on a lot of community subscriptions. The ones that returned HTTP 500 errors were listed in the "fail" list that the importer script generated, but a whole bunch of others returned 404 errors and weren't listed in either the success or fail lists.
So I advise those running this to pay attention to the error log to avoid losing track of those communities rather than trusting the "fail" list.