"I'd say it's far from perfect actually..."

Absolutely. Loads of nasties. But I think it is a better compromise than the Pro-Render compliant example for showing light interaction.

As far as that aspect goes, the most pleasing is the post edit brightened effort with shadows at 100. What's needed is a way of getting that level of illumination without side-effects. I think the answer to that is probably having True Ambience work with linear falloff. I get the feeling it works at squared.

But somehow I don't see True Ambience as a priority project in Bryce6.