Whats actually annoying is seeing a load of people who arent really quite sure what they are on about giving advice on an issue that they arent sure about either. Having lost engines to detonation myself, and knowing theres no way of telling what damage has already been caused I definitely wouldnt be risking the £3K+ repair bill if something is going to drop.
People still bang on about clicking axles like they are the antichrist, but what actually happens with them? Your axles click, big deal.
Ive just lost an SR20 bottom end because a ring broke up, probably from damage caused before I put the engine in my car, certainly not from me running it, but hey, its not as bad a as few clicks at low speed is it? Guess what as well - SR20's also have knock detection but for some reason it didnt seem to work in this case, like it didnt on the EJ20 and CA18 Ive also lost through detonation.
All Im saying is go in with your eyes open, manufacturers dont tend to reccommend a higher octane fuel just for a chuckle. Chances are the engine would be fine, hell, Id probably even bet on the fact you wont see problems but if someone openly admitted using the wrong grade of oil youd walk away, wouldnt you?
How relevant is you losing three engines that are not 350z engines? None.
Until there are hundreds of 350z engines going pop through detonation, as opposed to one that we actually know of, then it's scare mongering.