Metal does not aid permittivity of radio frequencies. It obstructs it. Check out all the phones which have metal in their bodies (6300,8800, N91, E50, etc.) They do not have metal in their top of their back sides (since thats where the antenna is). My sister had a 3220 which supported cut-out covers at back, but nokia mentioned it in their user guide that the cut-out covers should not have metal particles in them, as they could obstruct the working of the antenna, reducing call quality, network reception and increasing battery consumption. In case of N95, the phone has 6 radio units positioned god knows where inside that compact body. So if metal was used anywhere, it might obstruct the working of one of the radio units. Tell me, have you guys ever seen a gps unit with metal on it?