Uh, oh, Roffe,
I see the budding of a new industry--reviving the guillotines.
You're right that we mustn't lose our heads over this!
Actually, the Guillotine design for a hammerschlag-sounding instrument has merit, if exactly the right soundboard and drop-weight could be determined. But somehow, for me at least, it loses the theatrical aspect of raising the mighty hammer, and the audience's anticipation, as they watch it fall.