Ben did say that he had not seen anything like it. it makes sense that you would need to stick to what the ecu has been mapped for, i.e. 97 octane fuel.
So what happens if you get a duff batch of fuel, that's only 95RON? You can't control that and that is why engine management systems run knock-control as a feedback loop on the ignition map.
Remember this is something that can take seconds to destroy your engine.
I cannot believe that despite no knock control there have been no detonation-grenaded motors running QPENG.
It's missing a major safeguard that pretty much ALL manufacturers use on their cars. It's so important that (as an example) the ABF uses
two knock sensors so it can accurately control the ignition advance.
Also, what happens if you rock up at a petrol station to find they only have 95RON on tap and you're running on fumes?
An AFR gauge won't tell you about detonation. That's what knock sensors are for. An exhaust temperature gauge might help, but it happens so quickly it's all over and done before you can respond to the gauge.
The only way of avoiding it with static ignition mapping is to run a massively conservative map, which will compromise power hugely. Even then, it's still a big risk to take.