I like the metric system. It seems to me to be more logical to let the physical constants and reality to set the basic units. Unfortunately after the French revolution, when they were standardizing the metric system, they screwed up the meter because they used the wrong figure for the diameter of the earth wrong. D'oh.

Still, the metric system makes more sense.

Unfortunately I grew up with the imperial system and I still 'feel' the imperial system in my gut. I know what 63F feels like. Tell me 17C and I have to think it through. I would never walk out the door and declare: 'It feels like 17C to me'.

I can estimate in inches by eye or using my hands. I seldom miss it by more than an eighth. Tell me 120 mm and I have to mentally convert to imperial and then estimate.