Yup. I did it when it came out...
Man im the biggest PSP nerd possibly alive.
I just been playing SOCOM fireteam bravo online with people... it isnt out yet, anywhere
For snes emulator, use snes9XTYL ... it runs mario all stars perfectly
For playing PSP games use UMDemulator 0.8 or devhook22... they run pretty much anything.
And soon as you downgrade, get wab version changer to make your PSP think its version 2... otherwise some UMD games wont work and will try to upgrade it.
Man I love my PSP
*plays metal slug*