I have just used the 'new' easy downgrader 2.01 on my PSP.
my PSP was originally version 2.01 and had never been updated.
It is fantastic - (noobz and the rest of the team you are amazing) the big advantage is you can downgrade any 2.00 or 2.01 PSP without GTA or any other UMD, and without needing to persuade a 1.5 user to copy their flash.
also there is no need to risk an upgrade to version 2.5 or 2.6
all I needed was (the amazing and free) eloader 98 this uses the tiff exploit to run homebrew and is used to fool the PSP into thinking it is ver 1.00
The downgrader itself (which runs under eloader 98)
And a real sony 1.5 update (which is readily available on the internet)
So I am now happily staring at 1.5 fw PSP
FEEDBACK ON THE UPGRADE
The eloader part was so easy - i hooked up the PSP and run the auto installer on the PC and it did it. to check it i went into the photos menu and the eloader menu ran straight off. i downloaded a game called squarez which proved it worked.
I found i had to power off after loading the game before i could use it.
then i loaded the downgrader and run it from the eloader menu - it failed with a module missing error - I powered off and on - same problem as the game the menu now came up and offered to change me to ver 1.00
all was well
next I went into eloader and ran the upgrade to version 1.5 - it just sent me back to the menu - i reread the instructions again i had done it wrong.
you have to run the update from the PSP's own game menu not eloader.
I did it again and the update went in fine and i now have a 1.5 fw
In conclusion - a very safe way to update to version 1.5, by simply fooling the PSP that it is version 1.00. Iw ould recommend it.
Noobz - if you read this - you and your team are gods
find it here - http://www.noobz.eu/ look for September 9th entry also find link to the 1.5 update there.