Hi spoon,
I haven't logged in for some time. I have just answered your PM and after that I saw your posts here.Luckily,Butters answered all your questions.In general you ask the same things,which I did earlier, so the solution is already written. Finally,you can downgrade to any version,but always have in mind that the first four numbers of the rgn file should be of the present firmware.
P.S - if you find a way to change the logo to Camper 770, please share how.
Good luck !