Nothing wrong with using metric, just be careful using conversion, better to stick to one system or the other on a given project. Conversion provides one more place to introduce error.
USA will certainly change to metric in the near future. All other english speaking countries have changed.
Not true the UK still measures speed and distance using the mile, beer, cider and milk can still be sold by pints, acres are used for land measurement, and weight in pounds is still used for some applications. Canada still uses Imperial or US Customary Units for certain applications like construction. Canada has a particularly awkward case where it uses Imperial in some applications and US Customary in others (they are not the same thing).
Very few countries have truly gone 100% metric. Even the French who invented the silly thing continue to use the Birmingham gauge to measure hypodermic needles, because that is what the world wide medical community have adopted as a standard (the metric system gave awkward measurements in that use).
Other common non-metric measurements used world wide include Fahrenheit for cooking, psi for tire pressure, pixels / dots per inch for video screens and printing, thread count threads per inch is widely used for textiles, BTUs are often used in metric countries as a measure for HVAC systems.
Conversely it is a myth that the US is a non-metric country, it has recognized and approved the metric system as a legal system of weights and measures since 1866. US Customary Units (not the Imperial system which is British) have been defined by metric units since 1893. Since 1968 packaged goods must be labeled with both customary units and metric units.
Where the US differs is that it has not imposed the use of the metric system, only encouraged its use and allows industries to adopt it naturally. It is highly used in science, and technology, the automotive and aerospace industries, little used in construction. Mixed in most other areas as the market demands.
