tried it at work today with my mates white psp, an it worked!! we were both very worried at certain points but we did it. but even though i created the update folder and put the eboot1.5 file in it, the update was no where to be seen, it downgraded to 1.0, then thankfully i had death jr in my psp which has the 1.5 update on the umd so i just used that, crashed at 99% like i was told, but after switchin off then on it was 1.5. like quiest said, i think theres as much risk buggering your psp up by officially upgrading either off a umd or network update.
