I have two DZ smocks, in TW and AR cadpat.
In fall it replaced my combat shirt, in all but the most brutal if winter I wore it over Arcteryx puffy’s and such.
Overseas it got worn over my armour as load carriage under my webbing on occasion.
Never wore the issued rain coat, mostly just my arcteryx alpha jacket. I had the luck of working in some very permissive and reasonable units when it came to gear. In the field anyway, Garrison was/is a different ballgame.