I read Ian West's enquiry about using E10 in his 1998 Toyota Camry. I would be very wary after my experience with a low-mileage 2002 Toyota Avalon. Perhaps it was simply coincidence, but when I tried E10 there was a slight improvement in performance, but it used more of it. After 2000 km the motor suddenly became hard to start, particularly in cold, wet conditions. The dealer said a rubber part in the tank had failed and replaced it. I switched back to ULP and the starting reverted to normal, but when I again tried some months later the starting problems returned. I vowed never to use E10 again and used 95 for the rest of the time I owned the vehicle! My present car - a Honda Civic - has a sticker on the fuel filler cap giving the nod to E10, but I'll stick with 95 or 98, both of which certainly improve the performance of a vehicle that goes quite well, anyway.
Your experience of increased performance and increased fuel consumption on E10 is in line with what we've been told would happen, but the failure of a rubber component in the fuel tank is cause for concern. So too is the starting difficulty you had. Both of your cars are claimed to be E10 compatible, but like you I'm not convinced that E10 won't cause some issues on some cars.