@Dianora @scott @VE3RWJ @HopelessDemigod
The only thing I've ever found in favor of non-SI units is that the foot, being based on 12", is easily divisibly by 2 and 4 obviously, but also 3.
That and Fahrenheit degrees are smaller meaning you needn't resort to decimals as often. The counter to that is that no one can feel the difference between 19 and 20 C any more than they can feel the difference between 67 and 68 F.