Peaches and FindingMyWay, your kinds of personal experiences with EMDR are exactly why the push for training in dissociation as part of EMDR training is happening. It is only through experience they have learned that extra consideration and an adapted approach needs to be taken with dissociative clients. I am sorry you guys essentially became 'guinea pigs'. They just didn't know what they didn't know. I really do believe that with a skilled and adequately trained EMDR therapist the process might be helpful rather than harmful though.

Yesterday I saw my new t for only the second time and I was so very impressed with her. She broached the topic of DID and structural dissociation and we shared quite a bit about my system and history. I was very surprised at how comfortable I (we) were in disclosing personal info to her. It was because she was knowledgeable, I suppose. She knew what we/she was talking about.
She was also incredibly perceptive and skilled at helping us to stay grounded. She noticed and responded to even very subtle changes in affect and switches etc, and was able to help us stay within the 'window of tolerance' throughout the session. The first time we saw her she taught us a tapping technique for grounding, and she taught us some more techniques yesterday. One of them was tapping to support during the session (like you with the buzzers, Peaches).
Near the end of the session she did a visualization exercise that safely contained everything and left me feeling so peaceful that I was able to leave the session without feeling triggered at all - which has never ever happened before in all my years of therapy.
We haven't discussed EMDR yet, but I recognize the techniques she is teaching me as part of the EMDR preparation phases. She is just so attentive to my dissociative cues and so effective at helping me to ground and refocus that it all feels very, very safe. She seems so intuitive and aware of the need for tolerance and grounding that I think I can trust she would only attempt EMDR with me if she knew it was safe. Somehow I don't think she will even try it for a while yet.