if it was 100% reliable and stable nokia would had put higher frequency than 600 mhz since the beginning.

I did o/c to 800mhz , it took only 5 minutes , and it's DAY and NIGHT , even if I don't play psx or java games.

Maybe when pr1.2 is released it would be safer to decrease to 750 or 700 mhz , if the update improve the phone enough.