In my model of the world, perhaps a brain slowly ramping down is a pleasant experience. That's totally conceivable to me. However the brain being instantly disassembled faster than it can have experiences would be the absence of experience, be it a pleasant or unpleasant.
But even then, we can't know the difference in experience for brain matter sprayed all over the room vs contained in one place.
A materialistic model asks us to question what happens when the material in question is rapidly separated and damaged, no?
Are individual pieces of cortex capable of experiencing distress for the minutes or hours in question? We have no idea.