This method is only for if your PS3 firmware is 3.6 or above (NOT tested on 3.70 YET)
If you're on anything lower, you can downgrade using a service mode dongle (PIC-based, ATMEL based, branded (E3 reader) etc) & the firmware PUP you want to downgrade to. There are specific files to be used with the different FW downgrades (LV2DIAG files)
So it has been awhile since any posts were added to this thread. So... I am being annoying and bumping with a question.
Theoretically, if I were to attempt to downgrade a later firmware than what is tested for this tutorial, what kind of problems am I going to run in to? I really want to downgrade my 3.73OFW (CECHA01) PS3 back to 3.41OFW. Does so much change between the OFW releases that the write paste files are going to be incorrect when it comes to modifying the dumps? Hit me back if you can.