The routes are known - YVR-HKG, YVR-LHR, YUL-CDG and YUL-LHR off the top of my head. You can always check by doing a dummy booking in J and see whether they show the second J cabin.
I believe there are 7 HD in the fleet. The other 12 are "almost HD".
Note it is 40 J vs. 28 J