The vitamix has an automatic cut off to save the motor if something is going wrong. It just stops working for a few minutes. I overloaded it once, and ran it at too low a speed, so the safety tripped.
Cleaning after making nut butter's not too bad. The butter is warm, so flows out easily. So after you've scraped out what you want, just add water, blitz it on high for a second, and you get nut milk. When you want to clean it, just add washing up liquid, and hot water, and run it high for a few seconds. Hot water and detergent moving at high speed cleans the insides very quickly.