I am new to rediff site,i went through the write up on communicating effectively.I read the views of others too.I will recall one write up i read recently in times of india ,I beleive some great literary personality of karnataka used to speak tamil in the kitchen,kannada in the streets,and english in the upstairs of his house.Probably what he meant was that language should be flexible ,communicable and people friendly.No fixed notion should be their as regards language.It should be used as per your audience ,situation and timing.