On the topic of "shared drops":
Part of the problem with shared drops is the armor class - both Moonkin and Shaman are spell casters who are looking for stats pretty much the same way Priests, Mages and Warlocks are (up to a certain extent).
However, they need to make exclusive drops for them just because they don't wear cloth.
How do you get around this problem? Tokenize all the slots that use an armor class definition. They're already doing this for T6: Helm, Shoulders, Chest, Bracers, Gloves, Belt, Pants and Boots are the 8 slots that are defined as having an armor class.
If these are tokenized, it doesn't matter how specialized the stats are: Plate with spell crit for Holydins, Mail with MP5 for Resto Shaman, Leather with SPI for Resto Druids and Cloth with SPI for Holy Priests.
And what of the other slots? Necklaces, Cloaks, Rings and Trinkets can all be made "general". INT, STA, healing and MP5 for a healing neck: It's not strictly optimal, but anyone will take it.
STA, Dodge rating, Defense rating and even Expertise rating for your tank cloaks - spell damage for the Pallytank? He gets it from his set pieces. STR for the Warrior? Set pieces. AGI for the Bear Druid? Set pieces.
Of course, you'd still get a lot of "loot clutter" in pre-raid dungeons where there aren't any set pieces yet, but since those can be reset instantly and run multiple times a day, the issue isn't nearly as pressing as getting
[Tome of the Lightbringer] from Shahraz for the 11th week in a row.