I've got an 80 year old kitchen scale that's dual measurement.
In order to make the conversions practical, the actual divisions would need to be changed. Of course it's not going to happen — it's more of a "thought experiment" based on my dislike of the sterile and somewhat artificial names of the metric units than a practical suggestion. But who uses "decameters" or "centiliters"? When I was in the army, kilometers were referred to as "kilos" or "clicks" because using the proper term was unwieldy. In the shop it's much more convenient to use customary measurements which can be estimated easily and divided into halves, thirds, and quarters. Obviously it's just what we're used to
but I know that some woodworkers in other countries also use non-metric systems which they find easier.
I like the idea of being able to use English words for common lengths, weights, and quantities. Go into a pub and order a "pint" instead of .5 liters, or a "shot" rather than 60 ml. Estimate a "mile" by counting a thousand paces, that sort of thing. People decry the loss of various languages around the world — I feel similarly about systems of measurement used in different occupations and in other cultures. But I realize that standardization is pretty much unstoppable.
As far as Celsius and Fahrenheit go, I'm (not surprisingly) in the Fahrenheit camp.