I converted to 14w04a a while back and here are my problems.
-converting to 14w04b, or any version newer, turns item frames into drops.
-reverting to to a previous versions completely deletes the frames as a whole and erases what's in chests.
MC-46598
Frames
Resolved
Duplicate
0
Romeo Paloma
(Unassigned)
Unconfirmed
Minecraft 1.7.4, Minecraft 14w02c, Minecraft 14w03b, Minecraft 14w04b, Minecraft 14w05a
Retrieved
Duplicate of two tickets, please search next time.