Hi Justin,
I have cracked it: Instead of using the arch-chroot, I created my own script with the following contents, and it just worked.
Code:
cp /etc/resolv.conf ~/chroot/root.x86_64/etc
sudo mount --rbind /proc ~/chroot/root.x86_64/proc
sudo mount --rbind /sys ~/chroot/root.x86_64/sys
sudo mount --rbind /dev ~/chroot/root.x86_64/dev
sudo mount --rbind /run ~/chroot/root.x86_64/run
sudo chroot ~/chroot/root.x86_64/ /bin/su - <username> -c 'DISPLAY=:0 reaper'
However, it takes over my sound card completely, so outside the chroot there is no sound .. any idea's? Do I have to use dmix?
Also, --rbind doesn't allow un-mounting (says resource busy) so you have to log out of session to umount everything .... guess I might try "mount -o bind"