UPDATE 3 - I tried again today with an access_token parameter, and I'm currently at around 400 requests 10 seconds apart without throttling. I'll let this continue to run for a while to see if there's any other strangeness I encounter.

UPDATE 3 - I tried again today with an access_token parameter, and I'm currently at around 400 requests 10 seconds apart without throttling. The requests continued to succeed until my quota was around 1717, at which point the access_token timed out:

{u'error_id': 402, u'error_message': u'expired', u'error_name': u'invalid_access_token'}