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:
-added anti move/delete protection of the ds vc title when in CBHC CFW
NOTE: this change (as well as the last update) do NOT AFFECT MOCHA CFW, they only affect my internal CBHC CFW which you can enable by just setting it to autoboot system menu which will give you full signature and region patching as well as this protection and re-applying patches on reloads; overall letting your wiiu and the menu run as they would normally