I'm curious as to what difference it makes what units are used to measure speed on aircraft. It doesn't matter if it is mph, kph, warp factor, mach, or some other randomly assigned metric. Who cares?
Being a proud American, it pains me to see statements such as, "We are at a disadvantage because it isn't the way we use!" You learned how to fly, you at one point learned how to convert inches into feet, feet into yards, etc. The point is that at one point in your life, you learned these tasks. Although it's been a number of years since I was in school, I recall quite clearly learning how both the Imperial system and the metric system worked. I also remember being taught how to convert between both systems. If they are no longer taught today, it only further proves exactly how poor the education system here has become.
It is actually frightening that such attitudes are prevalent. Why doesn't everyone speak like we speak? Why doesn't everyone use the same money we do? Why doesn't everyone ..... sorry, I guess I got off on a little tirade.
Instead of claiming ignorance, and then using that as an excuse, use your brain. Figure it out, and quit proving the "Americans are a bloated, gluttonous, power-hungry bunch of ignorant salamanders" image that prevails throughout the world.
Oh, by the way, 1 mile = 1.609344 kilometers.