My personal results switching from Rogero CFW 4.30 (v1.0) to REBUG 4.21.1 REX
PS3 Model: CECH-2501A
1- Downgraded Rogero CFW 4.30 (v1.0) with REBUG '999' Downgrader 3.55 via Recovery Mode.
2- Installed 'Toggle QA' + Run 'Toggle QA' from XMB.
3- Dehashed via Recovery Mode by installing Rogero CFW 3.55 (v3.7).
4- Verified Toggle QA key combo from Network Settings, all good.
5- Installed REBUG 4.21.1 REX via Recovery Mode.
So far as another used reported, Need for Speed Most Wanted (requires FW 4.25) did not work (unmodified), at least using multiMAN 04.09.00 + BD-Mirror + Standard BD-ROM Emu, so I guess I will need to resign games that require FW 4.25+, but that's OK, this CFW is very nice .
Thanks to REBUG Team for this nice release! I hope to see a REBUG 4.30 REX at some point.
EDIT: Decrypted/Resigned EBOOT.BIN from NFSMW for FW 3.60 and loaded just fine
EDIT2: I know is offtopic, but for those wondering how I decrypted/resigned, here you have:
Note: Remember to store a backup of the original EBOOT.BIN just in case.