T1 uses IFS and I have DID. I think it is useful for understanding the different parts. The ultimate goal of IFS is to have all parts work together, which is not all that different from the goal of integration. I have had some parts just start always thinking and acting together without me really trying to get that done. And I have had others just quiet down and trust that the others will take care of things. And I like that-not matter what you call it.