Oh - given that usually most of your researchers are fairly useless in combat ( almost any mage with no more than 1 level of magic ) you don't _want_ them getting into it. On the other paw, if you're getting indie mages with 2 or more in a path (main one I can think of in Dom3 being crystral mages and a fire mage school) you might want them out in the open doing double duty as research/defense.
But generally? Use a fort to keep them mages alive. Not many players take the time to script _every_ researching mages for combat - but when someone attacks your fort, you dang sure do.
