You seem to have forgotten that Britain likewise suffered, and in adressing British people, who lived through it, or whose parents did...that was a faux pas....or bad history.
Pethi, Reader, in the few and far between when the GOA has them, unless they are suffering from pomposity, or you sare speaking liturgically (in Communion lines, commemorations, etc.) or formally can be addressed by their first names. In the GOA we create Sub-Deacons for about 40 minutes, though...and typically, you wouldn't be adressing them during the Liturgy while they are doing their prayers. Other jurisdictions, though, that DO create Sub-Deacons of longer duration, pethi, please, in writing, address them properly. PARTICULARLY when there is an age gap.
Conversationally among peers you have known since before you were ordained? Tricky....up to the clergy in question. When in doubt, be respectful.