Click here for an article about Opus Dei from the National Catholic Reporter (NCR). NCR and the Jesuit weekly America are probably the top left-of-center Catholic publications in the U.S. I subscribe to both, and have never seen a favorable word about Opus Dei in either publication. However, I'd say their attitude toward Opus Dei is disdain, not alarm - although there was a general expression of disgust when Pope John Paul II showed favor to Opus Dei by declaring it a "personal prelature" and beatifying the founder of the organization.
This article (click) in the Journal News (Westchester, New York) gives a pretty good explanation of the organization and its work.

I did a fair amount of checking, and still can't see any evidence of a Jesuit-Opus Dei connection (although the Jesuits haven't been overly pleased with the general this Pope appointed for them). One of the Nostradamus sites has some wacky stuff that ties Opus Dei with the end of the world and all the hooey that goes with that, but I refuse to put any credence in that.

There is a lot of spooky information out there - this site (click) shows incontrovertible proof the the Jesuits assassinated John F. Kennedy, and Opus Dei was also involved somehow.

But no, no evidence of a musical tradition.

-Joe Offer-