I've been using PersonalLootHelper up until now to see who can trade their drops.
Although the addon is not really accurate. It sometimes doesn't catch that the player can trade a ring or can't trade an off-hand.
From there I just ask the player if he needs it. If yes he keeps it, if no people roll and it gets traded away.
That's just a band-aid method right now. How do you guys handle loot? Are there better addons out there?
Edit: Should maybe add that this question is for mythic guild groups, not pugs or casual groups.