For me I looked at it like this, I have a 226 trinket, a 232 weapon, and a 232 shield. The trinket would be my biggest upgrade so thats settled, get the key with my first 60.
Ill grab offset pieces for the time being, cause you can't even attempt heroic anything till you kill the Lich King on normal (right?). By then ill re-evaluate the tier and figure out what direction I want to go. But historically I have found 2pc to be as far as I need to go with tier, off set items just seem to be to good to pass. Been the same since kara IMO.
There is something so appealing about backhanding someone across the face with a shield.