This is a guess, but here goes. The Vortex XD glass was always a Vortex method of designating their ED glass. Extra low Dispersion ED. In Vortex parlance eXtra low Dispersion XD. I would bet that this objective lens glass is still there and has not gone anywhere.
HD glass usually means High Density. HD glass is usually a rare earth mixture, usually Lanthnum Crown Glass. This is an ocular lens glass and used as an field flattener. If you look, there is a difference in fov in all the new HD binoculars. SInce fov is an eye piece design function and HD is an eye piece glass, my bet that we see here binoculars with ED objectives and HD eye pieces.
I bet we see a lot of that from SHOT releases.
Then again I may be all wrong too.
