I struggle with Metric, only because the damn MPH's on my speedometer are larger than the KMH... At the end of the day it is what you're familiar with, or more appropriately, the environment you're in. The whole 'nature vs nurture' questions that come up in biology a lot.
I at the VERY least use mili/micro/nano for inch measures at work. The whole 1/16th 1/32th crap with inch measurements makes me sick, the person that thought it up should be drawn quartered and shot, right after everything they've done is converted <G>