Hunting Heralds with mf

Hi everyone. Brand new Warlock player here, with barely over 100 hours in-game.
(I play offline, no Enigma, no Infinity, yes sunder charm)

I'm still scrambling to find my mf method before I settle for those long farming sessions.
I found that targeting T5 Heralds is pretty compelling, in spite of problems with their design (having to full-clear without sunder to get a sunder).

Now here is my point:
Would you ever choose to farm T5 Heralds over act bosses, cows,

Lower Kurast? And to farm entire tz games over single tz zones?

Herald drops have been nerfed, but combined with tz drops and exp - is it still a complete waste of time?

From Pavke's reddit post: From Herald description: