Hmmm. The only issue I have in terms of 'knock retardation' etc is that if the petrol is rated at 98 RON, is it tested including the ethanol? If 2 fuels are 98 RON rated, and one is ethanol blend, then neither should have advantage over the other.
SAFF would theoretically allow MORE timing if they start with a 98 RON base and add ethanol, rather than a 96 RON base and then adding the ethanol to make up to 98 RON. (Ethanol has an octane rating of ~110) Might be worth firing off an email to SAFF to see which option they take to make their 98 stuff.