JustEmily: I think you brought up a very cognizant point. Through my education I have a tad of knowledge of Neurology, but for more layman reading I would recommend reading,"Phantoms In The Brain" by V.S. Ramachandran. He was the one who actually invented the 'Mirror Therapy', and explains the theoretical rational behind this and other near-phenomena. To put it simply, it is fascinating. I feel it is a very rational idea to use this in GID therapy, or even to elucidate closer to the origins of GID.
For example, imagine an fMRI study that compared a cis-gender Male/ Female control group to a group of GID individuals (FTM/ MTF) and they all undergo this visual/pseudo-tactile reflection of another gender. As a quick side note, an fMRI shows where blood is going in the brain, and thus shows us what parts of the brain are active. This could provide the medical community with data that could help us closer answer questions like: How do cis vs. trans individuals react differently to gender in-congruency? How long does it take to be in the correct gender for one to neuroplasticity to adapt (e.g. get rid of their dysphoria)? What is the physiologic neurology of dysphoria? What parts of the brains are augmented when a transgender individual is 'in' their correct gender? These are questions that could be answered that could improve treatment outcomes, and ultimately could lead to the development of new therapies.
SuchisLife, thank you for posting this

On a person note, I would really love to do this!!