Looking at the screenshots, I’m not sure that the outline-smoothing is an improvement: to my eye the steps of the original jagged outline are still rather visible, and the blurring seems to largely have the effect of making the outlines fuzzy.
(I’m sorry to say that I don’t have a better option to suggest, however. I’m far from an expert in graphics techniques, and while I’ve been thinking on-and-off about something similar the only option that I’ve come up with is supersampling, which seems likely to be expensive. :/)
That said, I do rather like the specular quantisation and the light-to-dark transition.