I have been using this model of shaver head for some years now, and am always completely content with it. It gives a first class shave straightforwardly with no fuss. (I'm also very well satisfied with Shavers service and delivery.)
I left it 2 years before replacing cutter/foil. You certainly notice the difference. Braun are right when they say 18 months. Used this company for some years now and they always give very prompt and efficient service.
Excellent service brilliant shaver god send for me would recommend 100%