Fly and feint can be very strong if played well, especially fly now you have two pivots. A shooting unit can move somewhere unchargeable and shoot, whilst also opening a flank to charge into next turn if the opponent doesn’t react to it.
I was wondering about the -CS1 thing myself. If CS1 is valued at 10-15 pts for a 15 attack m4 unit with fly (the magic formula values things like CS higher or lower based on a unit’s ability to utilize it such as more attacks, me3, high speed etc.) then the increased cost to the unit to give them a 12” shooting attack is more like 70-75 pts which feels mental. Without looking through the other armies the only other unit that comes close to that penalty are the Lionsnarl cav that lose TC2 to gain shooting attacks.