Good post.
The most important aspect of this chart is the total dynamic range which is measured from the top of the yellow to the bottom of the green. It is always better to record on a medium with more dynamic range. Headroom isn't as important because Permitted Maximum Levels (PML) are arbitrarily defined.
Rather than reducing the volume to transfer a recording from a high dynamic range medium to a lower, it is better to use compression. Just reducing the volume will lose the lower ends of the recording in the noise floor.
Recording engineers who do mastering to vinyl tend to be really good at using compression to reduce the dynamic range of recordings. Since Vinyl has maximum dynamic range of 52dB and CD and DAT have over 80dB range.
True high fidelity recordings make use of the entire dynamic range that is available. This is contrary to the way most recordings are mastered today as a result of the loudness war. Wikipedia has a good article on it (
http://en.wikipedia.org/wiki/Loudness_war ).