As Julie's experience, find it hard to note anything that would be considered significant and needing to utilise a revised specification.
Pinking, knock etc are primarily influenced by octane rating, which if unchanged for E content can't drive a shift.
Commando combustion chamber very significantly differs from these small four cylinder designs and likely respond in different way.
The 400 appears to be fairly well optimised for this in regard to timing, but wouldn't preclude experimentation if you're willing. They seem hard to detect pinking under load though and you may not detect much in the way of fault, or even any improvement that's measurable.
