Safe way to play online with cfw?

Hi, im currently on lastest official firmware 4.31, and i wanna get a cfw mainly for emulator and also homebrew, but i still want to be able to play online with my cd version of gran turismo 5, ive heard that some people can play online without getting a ban on a certain cfw, and turning off internet when playing homebrew.

I was wondering what would be the safest cfw to play online? And how i could downgrade it from 4.31.

Thanks.