Recalling one of the major complaints about the pre-3.3 lighting system, I've been doing some comparisons of the dark sides of planets with the prototype lighting balances disabled. I can confirm that it's the brightness skybox that is responsible for the apparent brightness of the dark side of planets. With the settings I'm currently using nights aren't as dark as with the default 3.3 lighting system, but they are noticeably darker than they were from about 2.2 to 3.2, or if I had simply turned off the prototype lighting balances without making any changes to the galaxy map, bloom, or glare settings.
I just compared driving in a canyon on Pleione 11 A to a video I had of the same canyon from back in 2.0, shortly after Horizons was first released (and my benchmark for how things should look). It's not exactly the same, but it's pretty damn close, and what difference there is in illumination is almost enirely due to having more of the nebula visible in the sky.
Also, back on the topic of shadow related changes, I've been playing with ambient occlusion settings, with the intent of making objects that aren't directly lit, or that are already in shadow, appear more grounded by making AO more prominent.
This is what I've got so far, if anyone would care to try it and post some feedback:
XML:
<HBAO>
<High>
<RadiusInMeters>12.0</RadiusInMeters>
<NearRadiusInMeters>4.0</NearRadiusInMeters>
<NearDistance>180.0</NearDistance>
<PowExponent>2.4</PowExponent>
<Bias>0.45</Bias>
<BlurSharpness>1.5</BlurSharpness>
</High>
</HBAO>
This can be dropped into the GraphicsConfigurationOverride.xml and replaces some of the 'High' quality Ambient Occlusion settings.