Movement is not smooth for blocks not normally movable
Blocks with extra data (like dispensers, heads, signs, etc) will not keep that data when moved. Blocks with inventories expel their contents when this happens
Moving blocks with inventories is not recommended due to server crashes that occur sometimes under certain conditions (ex. pushing a dispenser underneath a hopper that is trying to insert something). This can cause slight world corruption where the server crashes again when the chunk containing the diseased block is loaded. Deletion of the block or chunk with an external tool should solve the problem.
Moving chests and trapped chests will cause the server to crash
