I've literally just swapped to the Shadow Priest from the Warlock (Lock since TBC, gets boring nowadays) right now I seem to enjoy it and it's cool, i've asked a few top Priests (Method/Envy) and they claim it's pretty much the same sh*t in 5.4 (Mage/Lock > Boomkin/Ele/Spriest) is that true? I'd imagine myself as a casual so I doubt i'll ever get full hc clears, so i'm not worried about being able to beat people in BiS gear with perfect rotations.