> Imperial is easy to eyeball and is in human sized chunks of understanding. Metric is precise and easy to do math with.

This is just what Americans think because they use imperial units for everyday stuff and metric for science. In countries that use metric for everything, people find metric units "easy to eyeball" and are confused by imperial units. In the UK we use a mixture of both to some extent. For some quantities (e.g. people's weights) I'm much more familiar with imperial units and they seem "easier to eyeball", for others (e.g. temperatures) I'm the opposite, and for others (e.g. short distances) I'm pretty much equally comfortable with both.

Anyway, an important part of the design of metric units is that they try to minimize the use of conversion factors. For example, take the equation "power = force x velocity". In SI, the standard unit for force is the newton, the standard unit for velocity is the metre per second, and if you multiply a force in newtons by a velocity in metres per second, you get the power in watts, which is the standard unit. To do the equivalent in imperial units, you multiply the force in "pounds force" by the velocity in feet per second, and then you have to multiply by the conversion factor of 550 to get the force in horsepower. You inevitably need some conversion factors in some places, but metric units are designed so that you generally don't need them in the most common kinds of calculations, while in imperial units they're virtually everywhere. This is the main thing that makes imperial units inconvenient for scientific purposes (along with the fact that there are often multiple competing definitions of the same unit, leading to frequent confusion). As a general rule, they are just as "precise" as metric units.