The biggest problems with the old Rivarossi/AHM locomotives was that pancake motor is a very weak link and they don't last. There is a fix, Northwest Shortline makes repowering kits for the old Rivarossi locomotives, but I don't know what they cost. The other problem is the "pizza cutter" flanges that the Europeans used to put on all of their rolling stock. If you are going to run code 100 track, they won't cause any problem. If you decide to use code 70 or even 83, you may find the flanges run on the ties and lift the wheels above the rails