I don't understand this post

More on this from Dan Worrall

It depends on gear. Every analog mixer has his own circuits. Mixer channel's and the output channel circuits could give an additional color or richness due to saturation (transistors, transformers, tubes - technology used to signal amplification, transmission and processing) or could be quite transparent (Apogee or some SSL circuits). Every element of circuit has his own tolerance of properties norm, so every channel could process the signal subtle differently. In addition - the biggest difference between analog and a digital signal summing is the crosstalk between channels in analog mixers which is also summed in the mixing bus. And this have real impact on the overall sound of summed (mixed) signals. So it is not a placebo. But: many modern DAWs and plugin technologies can emulate this hardware property (Studio One can do it, iZotope plugins can comunicate between DAW channels, many of Plugin Alliance plugins can emulate subtle differences of circuit elements in every instance of the plugin). And if you can smartly use this features you can emulate this analog mojo quite well. In addition the modern digital signal processing technology gives you more control over the behavior of uncontrolled properties of analog devices (eg. the noise level, crosstalk level etc.)
Of course, analog summing on high-end hardware (eg. SSL, Neve, API) will always sound great, but I think the digital technology is in quite high level now, that it is better to use great plugins and modern professional DAWs then budget hardware. And the last: every summed signal, no matter with analog or digital technology, will sound great when the mix is great.
... ups... I'm sorry I little plowed your survey :)