The entire reason for you mentioning the metronome was from an earlier poster wondering why Jello used it, so I'll start there... You also called Metronome a "badass trinket" if you have a good titanforge.
#1 Desolate:
https://www.warcraftlogs.com/reports...mary&source=17
#1 DI:
https://www.warcraftlogs.com/reports...mary&source=15
In both public logs - 905 metronome... Therefore, I do not believe a "920+ forge" is needed to outperform a 900 whispers.
-
Also, I don't believe I missed anything... You mentioned not seeing a Metronome above 880 in all of your "heroic and mythic clears". Heroic drops 885 and mythic drops 900, so you've either not cleared it on any difficulty above normal, or the item was never given to you because it's inherently higher than your "880" comment used to prove "rarity" over whispers.