In the Latin West this is all entirely true and well said. However, it is not quite true of the Eastern tradition which I believe is also embraced by Miles Jesu - a very fine ecclesial movement in my opinion that would be enhanced if they embraced better music.
Yes, I have had some contact with MJ and find them to be very good and holy people. On the Western side, they seem to be closest to what I would call a Christendom College position: very conservative Novus Ordo--I have assisted at several of their NO masses where the priest was ad orientem--and the homilies seem ofetn to work in some reference to an older book, like Ricciotti's Life of Christ (from early 1940's, and perhaps better than Sheen or Sheed or Guardini) or Garrigou-Lagrange. I think in the early years they sent their clerical candidates to Christendom for initial training, in fact, and I know some of the Christendom heavyweights have been to MJ functions.
I have also assisted at MJ Divine Liturgies, including a memorable one at "Path to Rome" in Vienna in 2003, celebrated by Fr. Alphonsus Maria Duran, MJ, the founder himself, among others. Their priests are biritual and on the Byzantine side seem to answer to the local Ukrainian Greek Catholic hierarchs. They do a lot of work in Ukraine, so this would not be surpirising. Unfortunately they are not here in Houston, so I don't get to see them too often.
The good thing about their divine liturgies is that they don't use the "Gather" type music, but stick to Ukrainian chant. However, I have to say that even the NO masses with the music are quite spiritual.