When studying the Montanists we have to recognise that the majority of the information we have comes from their opponents, who recycled the same accusations slightly different forms (See John De Soyres work [http://www.earlychurch.org.uk/montanism_desoyres.html]). These snippets hardly paint a balanced picture. For example:
1) Monatus was a recent convert [i.e. not grounded in the faith – bound to be led astray into error]
2) He was from Phrygia [They are all mad there]
3) His first converts were of the female gender [Weak-willed and easily deceived]
4) They left their husbands [Shame on them!]
5) He prophesied that the new Jerusalem would descend in Phrygia [the arrogant cheek!]
6) The Montanists introduce new fasts and forbid certain foods [Think that innovation is a sign of inspiration]
It appears to me that the opponents of Montanism may well be using stock accusations used of other heresies in their attacks. Is suspect that this article may be relevant here:
V. Burrus, “The Heretical Woman as Symbol in (bishop) Alexander, Athanasius, Epiphanius, and Jerome,” Harvard Theological Review 84 (1991): 229-48.
I think that it would make a good Ph.D thesis for someone to examine all the accusations made against the Montanists and see whether the same charges were made against other heresies in order to test this theory.
Please let me know if you take up the challenge.