I have downloaded the source for the 'Precomputed Atmospheric Scattering' method, and they are still VERY heavy on the shader computations. I know they claim to be 'fast', but compared to the elegance of the 'lookup table' methods, its hard to just ignore all those extra instructions. Plus you lose a lot of artistic control when you use such a math based approach.

It seems like there should be a third technique, a sort of middle ground between the two...