If you're doing aerobatics in controlled airspace or over an aerodrome, I'd prefer you have mode C off. This is because another aircraft will not come near you as the controller shouldn't allow it.
Lets stop fitting TCAS then cause the controller will not let two aircraft come close to each other.
Turning off safety systems (mode C, TCAS, Conflict Alert) can have disasterous consequences as we have seen.
Regards,
DFC