i think i may help you on this one and these links all work to let you play online with your 3.55 cfw but you asked about the other cfw yes you will need to go back to stock witch is not hard then put any cfw you want on your ps3 3.55 ofw. ok lets start first you will need a spoofer 4.31 here is the 4.31 spoofer -------->
You must login or register to view this content. plus i have a link for getting you off a spoofer back to 3.55PSN Spoof Disabler [3.55] [KMEAW].rar
You must login or register to view this content. they you go bro with them you can play online just watch out you can get banned if you do mods but enjoy hope i helped you out