Installing just Haxchi is perfectly safe and will give you simple channel access to other homebrew programs without the need of the browser exploit anymore.
Installing CBHC though is FAR, FAR more dangerous but will allow coldboot into patched menu/homebrew, read this for more information:
Changes to CBHC:
-when starting up the console with system menu autoboot CBHC will now start the menu into mii selection if no default mii is set instead of just using the first mii
-added system reload patches to CBHC, thanks to dimok for patch location and elf patcher!