again, i think it depends on the fish themselves, right before you wrote this i was attempting to see what would happen if i put my blue DT in with my guppy community tank. first, he striped really bad, ive never seen one of my males stripe up before. so i gave it 30 minutes watched closely and he swam about getting adjusted , he didnt seem to care about the other fish, but, then all of a sudden the guppies swarmed him, didnt nip at him, but they were just curious i guess. i took him out, i figure that the stress on him isnt worth it. i guess i coulda tried longer, i just didnt wanna tempt fate.
good luck if it works for you.