Have done about 3500km's now on the CU2 Euro, nearly emptied the tank on the last run so now I'm pretty sure 90 - 95% fuel in the tank is BP Ultimate 98.

Still get the "metal ball in baby rattle" sound but it is not noticeable enough for me and I've stopped worrying about it and put it down to a characteristic of this Euro.

Interestingly, I have had a close look at my CU2 fuel cap and it mentioned that the CU2 is "Ethanol fuel suitable"!!!