I have just found out something. I remember sk group saying something about not being able to downgrade below 2.46 or something
But, i found something out! You CAN if your fw supports it! I have been able to downgrade my 20GB Launch Console to FW1.10!
I haven't been able to downgrade my friends slim to 1.10, maximum I reached was 2.76
I also have a FAT PS3 which came with 2.26, I was able to downgrade it to 1.51 but it was buggy (BETA Code I guess)
So, if we can make up a list like this, it would be awesome!