Without digging wayyyy too much into specifics and neckbeard stuff (unless you’re interested, in which case I can elaborate), IQD has done quite well thus far. I’ve had many quantums eaten for mana to healers but overall I’m happy with it. I’d avoid it on Guardian of the First Ones because I’ve never had the 2nd one NOT get eaten by a non-stat use. In my current raid team (shout out to based Cvlt), I’m given PI on a regular cadence as well, which helps further increase the value of Quantum (esp when it gives Mastery). I’ll let my logs speak for themselves with a 97.2 best performance avg as of this post. If I had a really high ilvl Ruby, I’d use that over Quantum. Shadow Orb seems alright too, and I defer to the Shadow Orb trink for Guardians of the First Ones.
252 MH/OH combo is definitely the safer bet, I just haven’t have a 252 weapon drop yet or it was only a vault MH choice (my only OH is 226 from CN).
I should note that in raid, I’m using a 220 cabalist trink in a 3-player book club. Not the most optimal but I never killed M Sire to get the 233 book.