I haven't been to IMS either (I once was driven past Spirit Rock in the way to a beach, but I don't think that counts either).
However, I haven't noticed any significant difference in Dhamma
as represented by talks I've heard from IMS stalwarts, such as Joseseph Goldstein, and what I've learned at an "Immigrant Temple". Which isn't surprising seeing as one of the "products" of IMS was the book "In this very life", based on U Pandita's lectures there. http://homepage.ntlworld.com/pesala/Pandita/
In any case, what I was trying to discuss in this thread was meditation taught with no mention of Buddhist concepts whatsoever, and how it was interesting that a teacher involved in one of those organisations found that various issues (such as anatta) popped up apparently spontaneously.