I have successfully downgraded my slim and kept my content. I backed up dev_flash3 and some other folder I can't recall till I get to my of as my Droid x's phone my of isn't working. Must have shut down the client on the of side last night. Anyhow I recall having to use the new flash rewrite app and edit the registry but got my psn content back.
PS3 CECH-2501A [CFW] & CECH-3001 [OFW]/ PS2 SCPH-3901 & SCPH-7501/ PS1 SCPH-5501
Mod Cobra 4.46 v7.00 w/ E3 Flasher [CFW] & Cobra ODE 4.50 [OFW]/ Mod HDD-OSD [Phat] & Modbo 4.0 [Slim]/ Mod MM3
HDD 1tb [CFW] & 640gb [OFW]/ HDD 640gb & OPL v0.92 w/ 1.5tb SMB