We have discussed the driver topic extensively in the D7200 thread, and the outcome was they are different drivers from the ones used in Fostex headphones: different diaphragm material, magnetic circuit, and suspension. May be manufactured by Fostex but that is irrelevant for the fact it's a different driver. The TX00 drivers are TH600 drivers. In addition, the driver loading (cups, Onken ports, damping) is different than in all Fostex/Massdrop headphone models.
In my experience the D7200 driver sounds quite different from the TH900 driver, which sounds slightly different (better) than the TX00 drivers. I have spent a long time with each, measuring response with and without cups etc. My opinion (based on available information, my measurements and my hearing) is that these are all different drivers.