If you go on maxroll drop calc, tier 1-2 1:328, tier 3-4 1:219, tier 5 1:164 for cold sunders, 0%MF, increasing MF makes almost zero impact on heralds.
Andy is the best with no quest, 1:7562 0%MF and 1:2742 600%MF. The highest non-unique is champion zombie blood moor TZ version, 1:107,878 with 600%MF.
I'm going to speak on behalf of the casual player base, this is nothing like season 3 or something when the first LOD sunders came out. In the first and 2nd sunder seasons, I was ignoring unique GCs and selling some to Charsi.
All the reports of people saying "it's too easy now, I found a sunder within 5min" - this is highly abnormal.
My opinion is that the drop odds are still too low for these charms to be "useful". For the casual player, it would be nice to have a sunder drop within the first 20 hours of gameplay or so, then work towards enigma etc. I really don't think there's much point in getting these after endgame gear has been obtained.
And before anyone tells me I'm too casual or noob, I actually found a sunder last season with a friend.
Its interesting if that's accurate, as it means the odds in p1 400% mf council are about 1:5350 per run, while andariel p1 400% is 1:2748, and p7p1 is 1:1775. The heralds ranging 1:338 to 1:169 for their special drops
that still puts the expected value of andariel or trav farming orders of magnitude more rewarding than grinding heralds, given all the other items they drop- and heralds basically drop nothing BUT sunders, and still at pretty abysmal rates for the time to grind them. Its hard to quantify their rate, but its not uncommon to only get 2-3 heralds per half an hour of a pub 30 minute TZ split game while you can do 30 second trav or 60 second andy pretty easily even with poverty gear