With my little experience of these 4090, only 3 benchmarks can be strongly improved by unstable memory : PortRoyal, Superposition 1080p and Superposition 4K the others not
Perhaps only these 3 benchmarks would merit a requirement to enable ECC and thus remove all current scores and thus allow ECC to be disabled for all other benchmarks.
This would make everyone happy I think and would be quite fair for all