You're right, Rowe, and I agree, faster is easier, but I consider that a shortcut that shouldn't be taken. Doing a fast roll is a good way to gauge where you're at, but not a good way to be thorough with your training. Its good to know you can perform it well fast. But perfect it so the technique is not dependent on the speed. You know?
*Yes, you really should use your arms. They are a transition point, so your shoulder doesn't take the impact*