I really wanted psp firmware version 1.5, and my friend broke his lcd screen by dropping a couch on it (durrr). So i took his and replace my motherboard with his. Now im running 2.00 (wanted web browser) and it runs sweet, just make sure you have a small enough screw driver (such as used with glasses). If you want any help on how to replace motherboards I am willing to teach you and you can also use these links.

For step by step (no photos)
Here

for some photos
Here

Where can you get a firmware version 1.5 motherboard?
Here
or
Here
(currently out of stock)

So if you really want to downgrade, take a look at price, $250 after you brick the #$%^er or 100-150 for a new motherboard.