I'm not sure if this has been discussed here, as this is my first post in afterdawn's forums, but I figured I'd let it be known. Having looked through other forums, I began reading into psp mods and firmware. I've previously had emulators on my pc, so I was drawn in. However, I saw many times about how going from 3.5 (which is what I started off with), and then going back from 1.5 to 3.5 could not be done. This is not true. I played around w/a few emulators, found that the snes emu was too laggy, and wasnt as happy w/the lack of features left on the psp. Then I went to my friends. He just picked up Killzone: Liberation, which I wanted to try out. When the UMD icon loaded up, below it was a prompt to update to 2.80, which it let me (I downgraded using the Lumines approach). So while doing this, I was able to take all the old Emu's/Rom's off, and now I have my PSP back to the way it was before. I was curious to see if anyone else has used Killzone for this?
Once I updated from 1.5 to 2.8 w/killzone, I used the 3.51 update my friend had on his memory stick. I have no intentions of downgrading again, the emulators seem to run much smoother on pc anyhow, plus it was missing too many features.