"Mack" is obviously spelled "Mac" in Gaelic. And just think of the MacKintosh "Mac" computers; people would be so surprised to find that they had sons and never knew it!
Sounds more like a name for a dog to me. A child would get teased far too much for the name Mack, it rhymes with so many things (Smack, Sack, Whack, etc). Also, it sounds like Big Mac and Macintosh. It's a strong, handsome name but just too easily teased.
I think this is a good name. The fact that it rhymes with slack etc hasn't stopped thousands from calling their sons Jack. I think Mack is a useful alternative to Jack which is lovely but now far too common.
Mack means "gas station" in Swedish. It was originally an acronym made up of the initial letters in the surnames of four men who manufactured pumps for gas stations: Mathiasson, Andersson, Collin and Key.