You're perfectly right with the disclaimer and i never thought this was intended to prove the superiority of one over the other.
It can, however, show a consistent difference. All clips were more 'lively' on the analog outputs, as if someone ran them through a very subtle exciter.
Or, you know, a non ideal analog circuit.
Besides, the fact that we're discussing this on a forum dedicated to an analog-circuit emulator only proves that we prefer non-ideal systems.
For myself, i'll take S/Pdif and an exciter any day. More predictable, less noisy.