I noticed it.
Car felt significantly worse to me running on E10, so switched back to using E5. Then, after a number of tankfuls, decided to give E10 another shot to see if it really was as bad as I remembered....Yes, yes it was so that was the last time I bought E10.
As long as E5 remains available (and my fear is that it won't be around much longer), I'll continue to pay the small premium for it, despite my car being approved to use E10.