The whole IMS teacher enlightenment topic is a long and complex one, and I don't have all the answers, but I can tell you what I do think I know:
1) IMS is one of the bastions of "don't talk about attainments" Buddhism and has spread that particular message for more than 3 decades, and this is a message that makes it hard to determine who there knows what.
2) In general terms, "don't talk about it Buddhism" is more prone to people getting fascinated with what they do talk about, namely psychology, being good Buddhists, whatever that means, and working endlessly on one's stuff and morality. The corollary of that is that they tend to be less into what this place is into, namely effective meditation in the classical, achievement-oriented, stages and states and paths sense of the thing.
3) There are some enlightened teachers to various degrees on the list. Exactly who is on the list right now and which are enlightened to what degree is anyone's guess, as they don't say, but in the past I have sat with people who were on the list who were enlightened to various degrees.
4) There are also people on the list whose attainments are questionable, but again, they don't say, so who can be sure? Much on this front is left to the realm vague conjecture, and this must suit them just fine, or they would do something about it. I could go into some specifics, but that's just more gossip and who benefits from that?
Thought about Spirit Rock? They are more on the "we will talk about it if you want to go there" end of things, as many of my friends who have sat there have reported. You may still run into some of the same issues as at IMS superficially, but it is easier to get to the good stuff.
I don't mean to needlessly bash IMS, as it is a beautiful facility with nice people that through the Forest Refuge is trying to turn things around as much as they can given the biases and taboos set up by their senior leadership and the considerable inertia of the culture they have set up there, but it is worth knowing what you are walking into there. I got a lot out of sitting there, personally, but the prevailing culture there is a potent force in a certain direction, one that this place is dedicated to working against.
Helpful?
Daniel
