I say all this with a big smile, you know
Quite frankly I don't know for sure. Sorry Dave, didn't mean to imply that you were saying anything about reciprocating assemblies - I just mentioned them because they are the types of assemblies that one really worries about with high rpms (at least with rpms far below what would destroy a flywheel)
DB is correct that there is a lot of energy stored in rotating assemblies.
I'd feel pretty bad if anyone got hurt in the end