The stability ball ab rollout is a great exercise if you don't have an ab wheel available. But it's also a good choice if the standard ab rollout is too difficult for you right now.
It's essentially a partial rollout since your body isn't going down as far. You can start with a large ball, move to a smaller one as your core gets stronger, and finally do the ab wheel with the full range of motion.
Hey, wanna tick a lot of people off? Want to start a flame war, a heated academic discussion, or just a good old-fashioned penis-waving contest? Then come out publicly and say that total body training is better than body part split training.