Debian Kfreebsd is not something I would consider to be really usable yet, especially since it will lack drivers you need (especially if you use AMD video hardware).
Arch (and any other rolling release distro) is not something I would consider on production machines, though other people will disagree here.
I would recommend that you set up a stable OS that you know for your working purpose, then use a separate machine or a VM to learn about other distributions without having them interfere with your production OS.
Last edited by TobiSGD; 09-04-2013 at 01:30 PM.
Reason: fixed typos