I've also experienced problems with lack of host/container separation with lxc on arch linux, e.g. shutting down container shut down the host. I suspected the problem was an improperly mounted/unmounted /dev or /sys in the guest.

I've had a much smoother experience with lxc on Ubuntu than arch. The core lxc developers work for canonical, and Ubuntu lxc bootstrap scripts are much more refined. Lxc support for arch linux is provided by the community, and at least when I tried last year, there were minor problems here and there.

On arch linux, I've found that systemd-nspawn support is much better than lxc's. The commands mkarchroot and arch-nspawn (in the devtools package) make running arch in arch straightforward.