I've done this with my pens and some of the pens that I am interested in. Because, I do NOT like FAT pens, nor heavy ones. Having measurement specs on my pens gives me a reference that I can compare other pens to.
The section diameter is tricky when the section/grip tapers, so where do you take the measurement. I like Robert's idea of a from/to (max/min). That would be the only practical option for a tapered section, since I may hold it in a different place than others. I've been using max-diameter of the section, but I think I will go back and add the min-diameter. Although that gets difficult for a pen like a Parker 51 that has no obvious grip, and the section starts at the tip of the nib. Always a problem maker in the bunch.
David's PDF is interesting as he specifies a distance from the tip 25 and 38mm where he takes the grip diameter. This is for 2 different grip positions. This is interesting as I currently hold my pens at about his 38mm distance from the tip. That takes care of the section diameter question for the Parker 51.
In my case, diameter and weight are important, length is not important enough for me to chart.
I also add measured tip width to my table, because some tips (ie Parker 51s) are not marked, that is my only way to size them.
It is quite interesting to see how the measured tip size varies between manufacturers and even within the same manufacturer. But I have not figured out how to record tip profile, as that also affects the ink line.