"What I've seen in other parts of the world--Iran is a good example--when represive governments are overthrown by religious movements, they usually end up being more represive than the government they replaced."

You're correct in one sense, but I think you misunderstand the motivation of the monks. Buddhist regimes are not oppressive as the very nature of buddhism is non-violent and compassionate. This is about the monks opening the way for democracy and the rule of law, not military rule and exploitation by it's near and even more oppressive neighbour.