They're great for PvP since you can dismount other players, and then throw both their tames and them in the air while building up charge to make the next blow even more painful. I have a secret tip regarding flyers trying to pick you off : you can right-click while in K mode so you can time your stun to when they are right in range of it (plus your "Head down" right click will send a flyer very far away once unmounted)