Regarding Champion/Bard
There is a bug right now where the second hit of Echo (ID: 1491526) does not get triggered, if any other skill does damage very shortly after the first hit of Echo (ID: 1491300).
As a workaround with complicated but doable lua, you would have to add a fake Cooldown (representing the time it takes until the second hit comes) on all skills after Echo is used. Also you would have to not use Echo, if you are predicting Perfect Storm to trigger between the first and second hit of Echo.
With these workarounds intact your dps is higher, but
1) they are difficult for the average player to implement in lua
2) ultimately cause dpsloss compared to the way Echo is intended to work
Suggestion:
Allow the second hit of Echo to trigger instantly similar like Tactical Attack from Warrior. Or just double the dmg of Echo if the required debuff is found on the target.
However, if time and resources are not a a concern, a full fix would be appreciated, such that even if a skill comes between the first and second hit of Echo, the second Echo does not get prevented.
EDIT:
Even a whitehit between first and second Echo prevents the second Echohit. Now this is very unfortunate, imo increasing the urgency because you cannot just stop whitehitting.