You should go to a higher firmware of custom firmware. I recommend using Rebug or ITA. For that you will need to downgrade to 3.55 then install them. It will automatically spoof the new updates so that you don't ever have to worry about that. DEX also runs smoother and gives you a better experience. As far as getting banned, DEX is also known to prevent most bans because you are able to use EBOOTs and SELFs, it's always better to mod using a Private Console ID, especially if you're trying to mod Ghosts, Black Ops 2, GTA V or those bigger, newer games. There is always a risk of ban but it's best to be as safe as possible.