Being in the science/engineering world, I use metric (SIs) all the time, and have since high school and college (it's not just MIT, BTW).

Being American, I would say that the decimal part of it makes things much simpler, but agree that relating the measurements to the "normal" imperial measurements used in every other part of my life is challenging.

I find that nautical miles are easier to use as a race officer. There are roughly 6000 feet in a nautical mile, so 0.1 nm is 600 feet, which helps when setting a starting line with a GPS.

Mike