My feeling is that the model of altar serving as “training for the priesthood” or even a significant pointer toward it is seriously overstated, certainly in regards to the Ordinary Form of the Mass.
I was an altar boy for 8 years prior to the Council, with all that implies: memorization of multiple Latin responses, knowledge of gestures, ability to serve at the Low, High, and Solemn High Masses, exposure to multiple priests in the same parish (usually for the better, sometimes for the worst). Training that demanded serious knowledge of what and why things were happening as they did. Ability to serve at Benedictions, weddings, funerals. At least a vimp when the bishop came, maybe a full server.
In today’s average 1-priest parish where the Ordinary Form is said exclusively, the server’s role is basically limited to bringing the cruets and the basin over at the right time, and carrying the processional cross reasonably upright. Their responses are those of the whole congregation. Benedictions are rare and far between usually, half the Church weddings aren’t even Masses, and funerals are handled by retired men in the Lazarus ministry. This is most certainly not a criticism of the Ordinary Form, but just an honest appraisal in terms of the degree to which the contemporary altar serving experience is far less “involving” in both the liturgy and exposure to priestly functions. Obviously any given parish may have a richer server role than this, but in general terms I think what I’ve outlined is correct. And clearly serving at the Extraordinary Form is a different matter.
So I really have trouble with the concept that altar serving as generally experienced now is a particularly significant pre-priesthood kind of thing. What I DO believe is that service at the altar provides exposure to both the “life of the Church” in general, and specifically the concept of SERVICE to the Church and God’s people. And to me those are lessons that cross gender boundaries. The priest’s involvement with whatever “youth ministy” the parish may have I think provides a stronger direct influence than do the cruets.