Thought I'd give some lightning settings a try. In all tests effects were turned off, because sunshine made it impossible to look at colour between pictures.

Testing without any AA, and outlines turned off:

First, stylized lightning. As far as I can tell this is some sort of smoothing mechanic.

With: http://i.imgur.com/S5SxL.jpg

Without: http://i.imgur.com/eKxeg.jpg

Doesn't really look good to me. Everything appears darker and less sharp, as if the black colours get smoothed out over everything around.

With:http://i.imgur.com/9pX9B.jpg 

Without: http://i.imgur.com/i3LfJ.jpg

Not only is there a distinct loss of sharpness here, but there's also a loss of colour.

AAx4 and outlines turned on

With: http://i.imgur.com/I9Dmz.jpg

Without: http://i.imgur.com/ptiJ5.jpg

With additional outlines (more black) and more AA, the stylized lightning looks even worse as it spreads all over. The grass changes from a green to a blueish green. The inn to the right loses almost all its textures. Also the fog of war is made distinctly more indistinct.