wow... Good research but too hard to read. The main reason I think is that those 3 letters are not a word, so some people may not know them, so it needs to be really clear that the letters are YUL. If it was a word like RED, I am sure a logo like that would be easy to read because people would recognize the word they know.
But I love the vibe... is it possible to keep this but make it easier to read?