1. This rule could be classed a "classic" along with rules such as the K&E Decilon, the Post Versalog (effectively a Hemmi) or the Faber Castell 2/83N. I'm not sure exactly why certain rules become "classics" but I suppose it includes a good range of scales and high standard of engineering.

2. This rule does have a few scales that are relatively uncommon. The LL0 and LL/0 scales cover ranges of log-logs very close to 1.0, 1.001 to 1.01 and .990 to .99. There is also a DI scale which, rather interestingly, is not on the same side as the CI scale.