Nickel silver us not magnetic regardless who makes the track RAF, that's why Magna-hesion died a death. I'm afraid one of the reasons front bogies derail is the old 'fine detail' problem. People want locos to look just like the real thing, they want to see light between the top of the bogie and the frame etc. so the bogie is made thinner and lighter. Back to back measurement is the main culprit though.