The PARAM.SFO can be edited, yes, but it won't help. The version will no longer match the version in the PSAR, which is encrypted. The only way the PSPD*zaster videos could get as far as they did is if they were fake. Otherwise, they would have had to edit the DATA.PSAR file to match the version info in PARAM.SFO, which you yourself just said is impossible. Quite simply, the videos showed progress that was impossible to achieve just by editing the EBOOT's files.

I don't put much faith in Mathieulh. He posted a nice long rant on the SXT website about how MPH stole about 90% of the downgrader code from Yoshihiro. Oddly enough, about 90% of the downgrader's code actually comes from groepaz' 2.00 Hello World app.