I am going to go out on a limb here and say that your wife would probably prefer to have you alive in 9 years than to have the mortgage paid off. You might want to check with her on that.

If your family is happy in your current home, then refinance to a nice 30 year mortgage and give yourself the financial cushion you need to allow yourself to cut back at work. Allow yourself to enjoy your life and your family while your kids are young. You will never get this time back.