I have tested the new mythic, for me is a solution looking for a problem.
If I have to nanny a 10s buff, watch every off-balance window and micromanage my ulti while paying attention to mechanics and positioning or my DPS abruptly drops by 50% may as well play a regular build which is (ironically given what I found appealing about HA builds) more forgiving while having a substantially higher ceiling.
The appeal of HA builds to me was a more forgiving/lower APM playstyle while retaining effectiveness.
This mythic, at least 'in my hands' fails to provide that.
Perhaps with better sources of Empower (like increasing the window from the MG passive to 20s up from 10s for instance, or making the Empower from Molten Armaments a group buff rather than a self buff) and better/more interesting supporting sets it might be a bit more interesting? Not sure, it still heavily relies on Power Overload and Off-Balance windows to be functional and that is not a playstyle that appeals to me.