Big red flag right here!! The Mass is, by its nature, unitive. By setting up "special Masses" for certain people that seem to be (but really are not) open to other members of the parish community, the Neo-catechumenals are contradicting an essential fruit of the Mass.
Separate liturgies eventually drained the Catholic Charismatic Renewal of any of its power.
In the interest of full disclosure, however, I'm jaundiced toward any group that smacks of exclusivity in the Catholic Church, including Opus Dei.