Yes and no!
I'm a therapist who uses EMDR as my primary method very successfully with PTSD, trauma, DID, and many other problems. It's a very gentle method with no "down-side" so that in the hands of a professional EMDR therapist, there should be no freak-outs or worsening of day-to-day functioning. *mod edit- advertising for book removed*
There is a ton of great research proving EMDR's efficacy and it is considered a first-line treatment for PTSD by organizations such as ISTSS (International Society for the Study of Trauma and Dissociation), American Psychiatric Assoc, Amer. Psychological Assoc, Dept of Veteran Affairs, Dept of Defense, Departments of Health in Northern Ireland, UK, Israel, the Netherlands, France, and other countries and organizations.
During EMDR you learn a lot of great coping strategies and self-soothing techniques which you can use during EMDR processing or anytime you feel the need. You learn how to access a “Safe or Calm Place” which you can use at ANY TIME during EMDR processing (or on your own) if it feels too intense. One of the initial phases in EMDR involves preparing the client for memory processing or desensitization (the 4th phase in the 8 phases of EMDR therapy). Resources are "front-loaded" so that you have a "floor" or "container" to help with processing the really hard stuff. One of the key assets of EMDR is that YOU, the client, are in control NOW, even though you probably weren’t in past traumatic events. You NEVER need re-live an experience or go into great detail. You NEVER need to go through the entire memory. YOU can decide to keep the lights (or the alternating sounds and/or tactile pulsars, or the waving hand) going, or stop them, whichever helps titrate – measure and adjust the balance or “dose“ of the processing. During EMDR processing there are regular “breaks” and you can control when and how many but the therapist should be stopping the bilateral stimulation every 25-50 passes of the lights to ask you to take a deep breath and ask you to say just a bit of what you’re noticing. This helps keep a “foot in the present” while you’re processing the past. Again, and I can’t say this enough, YOU ARE IN CHARGE so YOU can make the process tolerable. And your therapist should be experienced in the EMDR techniques that help make it the gentlest and safest way to detoxify bad life experiences.
Do for DID, as with any complex PTSD/trauma, the "front-loading" of resources, and a phased treatment plan is essential. Please read the 2011 revision of International Society for the Study of Trauma and Dissociation (ISSTD) guidelines for treating adults with dissociative disorders (available for free public download) at the ISSTD website:
http://isst-d.org/jtd/GUIDELINES_REVISED2011.pdf