From E3 4.30 to Rogero 4.30
I can now comfirm that it works going from E3 4.30 (installed over OFW 4.01 using the three musketeers patch on a PS3 which was shipped with 3.42) to Rogero 4.30 using Rogeros 425to355.pup.
This was my route:
E3 4.30 -> 425to355.pub from XMB -> enable qa -> OFW 3.55 from recovery -> Kmeaw 3.55 from XMB -> Rogero 4.30 from recovery
So FSM using a downgrade dongle is not necessary.