The Montreal International Jazz Festival offers a broad palette of styles covering disparate jazz formats, and, like the New Orleans Jazz and Heritage Festival and most other “jazz” festivals in North America, adds a significant dose of popular music acts to boost attendance.

This year Trombone Shorty and Orleans Avenue and the Soul Rebels were back at the Montreal Jazz Fest along with Galactic. The Soul Rebels headlined the same stage where they supported Shorty last year, but the news wh...