The shadows that appear on npc faces, especially under the eyes, look ridiculous even on ultra settings. In fact they look less intrusive on low, but of course that ruins all the other shadows.

Is it possible to disable just the on-character shadows, leaving the ground and building shadows intact?

No, I have tried it.

bActorSelfShadowing=0

-doesn't work anymore.

Balls! Oh well, thanks for the quick answer.

It's a shame, the rest of the shadows can look quite good, but the self shadowing is a pain to get right without killing the framerate.

What's your fShadowBiasScale in SkyrimPrefs.ini set to?

It should affect the minimum distance at which shadows are produced from surfaces. If you increase the setting a bit it should eliminate self-shadowing on small detail like faces.