Is very expensive because it is virtually indestructible. Life expectancy of 25-100 years. It is not encouraged because roofing is a very specialized and hazardous field. Roofing contractors are trained in their field and generally do a job that both lasts longer and has none or few mistakes. Loss of insulation is caused by the result of poor ventilation that leads to heat and moisture buildup in the attic area.
Prevention is of course the best action.
A qualified professional should check your roof at least twice a year. Also, keep an eye out for leaking, cracks in the wall and peeling wallpaper.