You have to be more specific. What classification, which profession, your age and what salary range. Those are important info to help you determine your choice.
And after tax income comparison is somewhat vague. If you are truly comparing after tax take then $20,000 is a lot though. Did you take into account of the extra deduction of your government paycheque, such as union due, superannuation, medical insurance?
But say if you are comfortable with the salary reduction and your lifestyle change as a result does not change much. I would say, go for it.