Right i have got an eboot loader that i beleive could work with 2.5.
I have got all the hello world files and the new eboot loader all zipped up ready to test on 2.5
I have 1.5 so i have no urge to upgrade right now but would like to have the choice.
Please have a go and tell me what happens with your psp.
There is a 0% chance of bricking as there is no need to access the flash and none of these files are harmful.
Thanks for the help.

Kind Regards
Richard Bru