Thanks for the guide.
Actually you wrote exactly what is my convern:
In the end JV costs 5 HP instead of TV 3 HP but does only minimal more damage ( although it is clear we will never pay the 5HP due to DP proccs) . From PvE POV the 100% more damage to a stunned target can be neglected.Justicar's Vengeance is clearly the choice when paired with T7 Talent Divine Purpose and/or you can cheese some stunable adds. You should consume Divine Purpose proccs with Justicar's Vengeance since it deals a bit more damage than TV does.
So actually why consider this talent over TV when you can do TV and get EfaE instead?
In the end I expec it to do more damage baseline, maybe reducing the additional damage to stunned to 50% and increase the base damage of JV accordingly to result in the same stun damage.
E.g. if 3 HP for TV is ~50k Damage at my damage, 5 HP should be ~ 75k damage. Then +50% is still around 100k damage to keep same ratio.... .