Quote Originally Posted by Ughmahedhurtz View Post
Apparently you're supposed to be able to, it'll just be a lower iLevel version (sorta like the 3 different versions of T9) for the LFR version of the raid. This is hear-say, and I can't even remember which forum I read it on. Could be completely wrong.
Straight from a blue:

Keep in mind we do intend to allow tier 13 set pieces to drop for those using the upcoming Raid Finder. Similar to the difference between normal and Heroic versions of tier sets, the Raid Finder set will have a lower item level than the normal and Heroic counterparts.

Set pieces from all three difficulty levels can still be mixed and matched for the 2- and 4-piece bonuses.


http://us.battle.net/wow/en/forum/to...33?page=23#456