I know this isn't a new problem but I'm a little late to the game. I just leveled up a shadow priest to get it to 90 to raid as disc. And good God if a priest ever has to move at a time that doesn't involve naturally refreshing sw the whole rotation and dps just goes down the poop hole.
Hunters warlocks and shaman can pretty much move and cast freely. Moonkin and mages have enough instants and mages have the talent to let them move and cast that they can work around having to move in a fight. Why are shadow priests the only ranged class not to have a good mobility ability? Every fight gets a "get out of the fire" mechanic and every ranged has a way to do so without losing dps it seems like it should only be fair that shadow priests get something too!