i think over the air 1.2 worked for me with about 90Meg free, so you shouldn't be far off. if these are your numbers AFTER freeing up rootfs then yes you have high usage. wouldn't worry too much though its a common problem, uninstall apps your not using (or just reinstall large ones after the update) look into the apt-get clean and apt-get autoremove commands (i wont blindly eccomend these without some research, apparently there can be problems, although i haven't encountered them when i use these commands) and see how much you can free. sorry cant help with flashing on a mac i'm afraid...