I just received my military green Bamboo pen, and I agree with you, it is extremely comfortable. However the hourglass sections on the 9B and on the standard Bamboo are fairly similar (perhaps a marginal length difference to the advantage of the Bamboo); so I think any significant difference has to be down to the shapes of their bodies, or the overall weight distribution difference. Although the Bamboo is wavy, its bodys thickness is more or less the same throughout, whereas the 9B severely tapers (thickest at the beginning, where most of the weight is situated).
thank you for the nice pics and description of the pens.
I decided to skip this group buy despite I am a great fan of Ranga pens, because I was concerned by the step down issue.
According to your description my choice was probably wise, as the step down is really an issue for me, due to the way I hold pens quite far up.
As you say, in the 9B the problem may be limited, while much more noticeable in the giant 9B (I have a similar experience with the model 4 vs model 5).
In that respect the 8B may look less elegant when closed, but it's ever so comfortable when writing...
Regarding the comparison with the Bamboo, since I also own a bamboo, it's very interesting to note, as you were mentioning, that surprisingly although the Bamboo does have a step down, its almost unnoticeable. It's probably due to the fact that the Bamboo has a very long section, in any case I can confirm.
Similarly (since we are on the topic) happens also with the Ranga Sugarcane model, very long section, no problem.
Nice to know the Sugarcane is similar in this to the Bamboo, unfortunately, however I missed any group buy on that. Ill have to look out for one.