When it comes to the small boats needed for creeking, slalom, or playing, the disadvantage of c-1 is the uncomfortable low kneeling position. With open boats like the smaller Esquifs, the paddling position is a bit higher, but you will take on water, and when you roll up, a lot of it will be in the boat. And the open boats do not have the shape needed for all the play moves possible in a k-1 or a kayak converted to c-1.
You will convert to open boat only if the single blade paddle quickly makes better sense to you than the kayak paddle. That will depend on you.