This is one of the main issues with recent Bhikkhuni ordinations by the Western Australia Sangha; the lineage was Dharmaguptaka, not purely Theravada, one reason at least for the Thai Sangha not to recognize those nuns. Other Theravada Sanghas do have less issues with them.
There are therefore different viewpoints to the need for specific formalities and the need to hold extremely strict to an orthodox reading of the canon; in Thailand, until 1902 nobody batted an eyelid when seeing a "fully ordained" Theravada nun and even in the Thai Forest Sangha were teachers who fully ordained women during most recent years -- they only did not do their utmost to squeeze the nose of the Supreme council in it after having explained their opposition to such a thing.
Edit, to clarify: the teachers of the Thai Forest Sangha I am talking about here were Thai and fully unconnected to the recent brouhaha created by Ajahn Brahm.