I use metric only when I have to. I wouldn't say that I hate it but I have no thought of what 100mm is until I convert it to inches. I have metric rules but I deal in inches as much as possible. Fractions do not bother me at all, I learned them long ago. I agree with Phil that feet and inches can mess things up sometimes. I find using inches and fractions largely solves that. My one tool that requires me to use metric some is my domino. It is useful enough to be worth the extra effort. I bought a DeWalt track saw, however, partially because it's depth scale is in inches. I see no benefit to converting. Inches and fractions work fine. I also understand that there are probably people who wouldn't know what 4 inches is until it is converted to metric. If that was me, I would be using metric.