I start several Xorg servers via SLiM via "systemd" on different virtual terminals (VT).
  • My video card driver doesn't support KMS, therefore the screen flashes. That is kind of tiresome.[/*]
  • Sometimes Zorg exits after boot with a message "xf86CloseConsole: VT_ACTIVATE failed: Input/output error". I guess it is because of races between several Xorgs starting simultaneously. It never exits if I start it manually by "systemctl start ".[/*]

So, I would rather switch VTs after boot by my script.