I've been following this thread for some time, aerobatics being my favourite subject. There are really two separate subjects here.
1. Aerobatics for special purposes, pretty much following the book and adhering to appropriate aircraft limitations.
eg
when Stuart Pearce looped and rolled the Nomad at Paris and other airshows in the '70's the aeroplane was in utility category and those manoeuvres were approved.
Neville Duke more recently at Farnborough in the Optica.
2. Aerobatics by cowboys with little regard for airframe limitations, effect on fatigue life and safety of passengers. Hearing about Skytoad roll a 172 recently didn't impress me - I advised the witness to tell the operator but I've heard no more.