Luci Ferson is saying that anything currently running OFW over 3.55 can only be downgraded using hardware. But are you saying provided the PS3 is 'compatible' with the 3.55 OFW, it can be downgraded to it even if its running a newer OFW 'WITHOUT' hardware downgrading.
But like I say, I'm now curious if it needs hardware flashing or there is some software / usb flash drive way of doing the downgrading - which doesn't need loads of soldering doing etc.
Any console running firmware later than 3.55 , Needs to be downgraded with hardware afaik , But don't worry it's not amazingly hard.
Find an older ps3 from cash converters etc that's in good condition , Play it for a good few days to make sure it's working as it should , I'd look out for a slim manufactured in 2010 , Then get yourself an E3 with the clip add on , Open the ps3 and flash it , Job done!