If you don't like the ghillie brouges (and many don't, so you are not alone), why not simply wear another style of black dress shoe? Generally, whatever you would wear with a tuxedo or a dark suit will be appropriate.

I personally don't think boots would be appropriate for a wedding. For walking about the Highland Games, or going for a Pub Crawl, sure. But boots would tend to make the outfit a very casual affair, and unless you are going for an uber-casual wedding, my vote would be no.