I had always been under impression, the original Russian saying literary means something else. Золотник (a piston valve) is the smallest, yet a critical part of a steam engine. Золотник (распределитель) — Википедия
So, I think an English equivalent of the saying "Мал золотник, да дорог" should say something like: "the smallest looking something/someone sometimes is the most important one".
As to the metric vs the imperial systems, the pros and cons are obvious. All derivatives of the measuring system employing part of the human body are more intuitive for the visualization and a unified system facilitates easier and more precise calculations and conversions. By the way, the metric system uses the basis of 10 for the number of fingers, but that is also not the most perfect one in all cases. For example, calculations on the sphere are easier and more precise to be done using sexagecimal system. Hanna, how easy for you would be to bake a pie for 5,400,000 milliseconds? Maybe, 5,400 kiloseconds is easier? Or 5.4 megaseconds?![]()