I attempted to run Xorg as a non-root user. However, I was unable to access my card no matter which dev permissions I changed. Non-root users' X logs indicated "no primary bus or device found" where root user had no issues. My best explanation is that my user lacks the (root) rights necessary to become the DRM master (for /dev/dri/card0), even though I provided the user with rw permissions to the relevant dev node. Per the information at http://hansdegoede.livejournal.com/14268.html, my understanding is that systemd and D-Bus (two pieces of software not present on my system) will provision these rights to users who wish to run Xorg. Reproducible: Always Steps to Reproduce: 1. Follow steps at https://wiki.gentoo.org/wiki/Non_root_Xorg on a system lacking systemd/dbus 2. Attempt to start Xorg as non-root user Actual Results: no primary bus or device found Expected Results: xorg-server ebuild should require systemd and dbus packages to be installed if 'suid' USE flag is not present. This is a hardened box with Noveau drivers (latest git, 9999). I have only partially tested this (did not try installing systemd/D-Bus to see if this fixes the issue) so it would be good if someone else can also verify that X will not run with this configuration.
There are several scenarios where x11-base/xorg-server[-suid] works fine without systemd/dbus. You are correct that running "startx" as normal user is not one of them. The suid flag being enabled by default is enough here, users who choose to disable it better know what they are doing.
Eventually succeeded in running Xorg as non-root -- in my case it was an issue of relaxing some constraints resultant from grsecurity options.