Kmeaw 3.55 to REBUG 4.21.1 REX

I just want to make sure and do everything correctly. Im a little confused on what exactly i need to do in order to ensure the best results down the road (online, future updates, downgrade etc...). I have installed the Toggle QA by rebug and verified i have debug settings.

Do i need to do anything else before i update to REBUG 4.21.1 REX?

Thanks

Current PS3 Phat 3.55 Kmeaw