I am smack dab in the center of Apple’s target demographic for the just-released Magic Trackpad—a MacBook Pro user for years, huge fan of Apple’s trackpads, and a consistent purchaser of Apple’s desktop mice. Note that I used the word “purchaser” rather than “lover” for that last one. I loved the one-button Apple (“Pro”) Mouse, but was less thrilled by its subsequent replacements: I was a…