The only item with a meaningful rating requirement is the heroic raid ilvl equivalent weapon (the 2200 weapon). However, unlike the LK seasons there is also a weapon equivalent to the normal raid tier ilvl that has no rating requirement.
All of the other items with rating requirements (ie: the set pieces) have the exact same stats as the ones without rating requirements, they're a free upgrade and just have a different texture color so you get a little bit of visual distinction for having a high rating (no gameplay advantage).
