I suppose it depends on the position of my hands on the keyboard. If I'm just doing light typing, say just simple e-mails or browsing, the position of my wrist avoids my watch touching the MacBook. But when I'm writing code or when gaming, I take my watch off. Otherwise my watch will bump against the palmrest and sides.
So far so good though, haven't had any dents on my BlackBook with a Moshi palmguard.