That could be a problem because a lot of people might naturally shorten it and call him Zack. D : Maybe a name like Zachariah, which is similar to Zachary, would be less likely to be shortened.
I do love Zachariah. It's so cool sounding. It's seriously Old-Testament in a country where even Zachary is out there, though. I'd love to use either as a middle name at any rate. Thanks for the input :-)