Correct, unless you have an Infectus Mod installed in the PS3 and dump your own flash files and then upgrade and use your own previously-dumped files to downgrade. That is the only way to do it at this time, and as mentioned if you upgraded already it's too late because each PS3's is unique so a flash dump from my PS3 wouldn't be of use to you and so on.
I tried playing around with this on FW 2.01. I had Ratchet gamedate on the HDD. I started F1 and switched with Fear. Played a bit. when i went to exit the game, you see the please wait then it seems like it´s freesing up, then I get the 3 Beeps and the Ps3 resets itself. When I went to see the Gamedata, it now has the Fear icon.pam video on the Ratchet gamedata. Now if I swap with Resistance the same thing happens when exiting the game.