Chris:
FWIW, I used a small angle grinder (DeWalt) with a diamond cutting blade. Tool (rebuilt, factory store) and blade was around $100. Trick is to bring your patience with you, and remember under the plaster is wood lath, or the dreaded black diamond wire mesh. Plaster of paris for patching works great. A sawzall vibrates everything, the DeWalt works like a circular saw.





John