From the graphic, it looks like MX-D will be a mix of the best characteristics from MX-P and MX-S, like an upgrade of both. Kinda like T19 is an upgraded/improved Tenergy, more dynamic.
Edit: Now that I'm looking at the picture again, I see MX-D is 51.5 degrees, so I think it's more Tibhar's attempt at a Dignics-like rubber. Just like MX-P and S were produced in response to Tenergy.
Probably their version of Rakza Z or Omega 7 China.