How risky is it to up and down from 1.5 to 2.00?
Took this from readme:

devhook FW2.50 with MemoryStick file root directry.
flash access is redirect to this directry.

You should be copy all files of flash0/flash1 and reboot.bin.
replace flash0/kd/*.txt with plain modded config files.

But I dont understand, its not proper english...
Whats a plain modded config file?