I've done EMDR many times & have had good and bad expereiences. Part of the protocol now though is to screen for level of dissociation prior to starting treatment as EMDR can make dissociation worse. I've mainly been treated with EMDR to process past traumas, but sometimes we use it as a means for me to go inside and talk to my different ego states. I don't have DID, although I do dissociate quite a bit - it's more like I have parts of my personality that are stuck at different ages and have different memories and personalities.

I've personally found EMDR to be very helpful.

--splitimage