I grew up with mostly the SI system. My father was into muscle cars, most of the cars I worked on (I was an aspiring mechanic) was SI. I started learning metric when I got into VW's as a teenager. Becoming a professional mechanic on ships, everything was SI (especially considering my first ship was built in WWII, my second during Vietnam!). But even then still knew that metric was the superior system. I justs learned how to use both.
But seriously, your argument is "English is the superior language because I grew up with it." Refusing to learn a second language because you didn't grow up with it doesn't make your ONLY language superior. That said, I only know English, though I have taken a couple semesters of Latin and one Spanish.
I'll take the metric system anyday over SI. But the reality is I have to use both because some parts of the world won't play catch up.
http://www.cnn.com/TECH/space/9909/30/mars.metric.02/