Yes, I purchased Rosmary's Split Wizardry. She is the GURU when it comse to splitting designs so you won't find a better tutorial on this subject.
Splitting designs is editing, not digitising so you don't need to know how to digitise to understand this, you just need to understand about the effects of underlay on a design, and if you have done any embroidery then you already know enough to get you started.
Good luck and enjoy, Meganne