All, firstly I would like to say how much I appreciate the change in the tone of this discussion from where it started out to a much more respectful exchange. I firmly believe forums such as this one should be a place of coming together and exchange of ideas. When we discuss thoughts, opinions and ideas and yes, even disagree on some things but do it respectfully, I think that all participants can come away enriched from the experience.
Sandy, a JXR 16f encoding would provide 1024 levels for each stop encoded. Values are determined starting at the sensor saturation point (mapping to 1.0) and halving the numeric value for each stop. As Emil points out, the numeric range of these 1024 levels is not constant, but the precision does remain proportional to the relative numbers of photons being captured on a per-stop basis.
Sandy, Emil, it may have too much fidelity in the shadows, but overall being able to avoid clipping seems like a bigger fish. That is the one we went after. In fact it was not the efficiency of the encoding or the excess fidelity in the shadows that caused the most controversy, it was the 'only' 1024 levels in the highlights (the corollary). Still, seems OK, and there's always 32f, or 16i if not.
Gabor, Agreed that it's all a bet on what photographers want. Only time will tell if it catches on as envisioned, as two distinct types of files as you've suggested, or even at all.