I'm sure you know this better than I do, but single dynamic range measurement is no proof of audible superiority of a noise shaping implementation.As such, I'm a little surprised at your "it's not worth the effort" comment and would like you to explain your opinion better, if I have misunderstood you.
I think adaptive noise shaping listening tests have indicated already their possible audible superiority over constant noise shaping curve implementations (regardless of what the average measurements for dynamic range imply).
I was under the impression that dither needs to be evaluated along with signal and not by itself? Am I mistaken? Not that I'm trying to refute what you say, so please don't take this the wrong way.
It is significantly more computationally intensive than the current fb2k ditherer, but still fast enough for use in (for example) an audio player, as far as I can gather from the papers.I haven't got the time to persue this right now, but if you need implementation details, contact the paper authors, and for example ask if they're willing to give out the source used for the papers tests.