I've been reading a lot, and experimenting with, Magic Find. Everyone seems to have a different take on how exactly it works, and I'm finding myself with my own as well.
I was wondering if maybe an official answer would be forthcoming if I asked here.
Here's my list of questions:
Does a higher Magic Find stat cause Magic Find to trigger more often when opening Dungeon chests?
When it does trigger, does a higher Magic Find stat cause higher-quality item drops when opening Dungeon chests?
Does Magic Find affect the quality of items found when opening caches at all, despite the fact that an announcement that it "triggered" never appears at those times?
If higher Magic Find does equal higher-quality Dungeon chest trove items when it triggers, at around what Magic Find level could we expect to get Shadow-2, 3, 4, 5, and Radiant items from Uber-6 Dungeon chests?
I've seen answers to many of these questions, but they are so varied, it seems no one really knows, and everyone is speaking from personal anecdotal experience. For myself, it seems for example that Magic Find does affect opening caches ...though most players say this is not true.
It is great to see you jumping in and getting involved, especially by starting with such a thorough and constructive first post. No worries, your formatting and method were perfectly fine as well, admirable even!
Hopefully I can lend some assistance in regards to information; everything I answer below is based upon tests or Developer statements that I have read in the past (though I do not have direct sources to cite at this time; I can try to hunt some down if you really wish it haha.)
Higher Magic Find does increase the chance of having a trigger occur whilst opening dungeon chests (as well as receiving random gear/equipment drops from enemies.)
When it does trigger, Magic Find causes the quality of the item dropped to increase by one level (I.E. Legendary to Relic.) Magic Find can trigger multiple times in one drop, allowing you to gain a drop that has "jumped" multiple rarity tiers (I.E. Shadow 1 to Shadow 4.)
Magic Find does not affect caches, chests, fishing, and so on. It only affects gear drops and chests that you break.
General consensus on the "best" threshold of magic find is blurry, though it was confirmed that magic find suffers from diminishing returns (meaning each point of the stat becomes weaker if you have a large amount stacked.) Having said this, I believe the 300-500 threshold is considered to yield the best trigger results (though such amounts are often not efficient or effective to use unless you have Dragon Spirit and Patron bonuses contributing to it as well.)