Rafal, most of the thiosulfate fixers/formulas (sodium, ammonium, other) discussed in Haist are hardening types, and therefore acidic fixers are the focus.
My sense here is that when it comes to serious photochemistry research from Kodak etc, there simply isn't that much out there regarding neutral/alkaline fixation. My two cents is that the interest in buffered neutral/alkaline fixation is a more recent phenomenon due to a few factors:
1. Less need for hardening during processing as current film emulsions are well hardened
2. Renewed interest in staining/tanning developers
3. Environmental concerns (ie interest in shorter washing times)
It seems to me by the time we all got really interested in these things, photochemistry research at Kodak etc had already essentially come to a halt. So when it comes to neutral/alkaline rapid fixation, we're mostly left to independent formulators/engineers. It then becomes more difficult to know with certainty what works (and how it works), what doesn't work, what is true or not, etc.