Full disclosure: haven't read the linked article yet.

My biggest gripe with the anti-metric folk is when they say it's too expensive, because we'd have to change all of our signage. That's bullshit. We replace our signs constantly already. Just set a date for the change, start teaching folks the system, and then on that date going forward any sign that needs to be swapped out anyway gets a new metric equivalent. We work with both systems, clearly marked, in the interim. This would be an excellent time to also switch to the vienna conventions on road signage and bring us more in like with much of the world. Set the date far enough out that anyone with a driver's license will have to renew before final metrication, and just have us all do a quick refresher on the new signage and speed limits and such before our renewal. Fairly low cost, as things only get swapped when they would get swapped normally.