Keith they all have good points and bad, the rubber or wooden shoes make the least amount of damage to the ground so for an experienced dog this is great as using an older cleave leaves less scent and less disturbance all round, the metal shoes give more crushing effect and more ground turnover and then leaving a larger footprint/ track to follow, great for a young dog just learning but making things easier for an experienced dog, but then for UKSHA/Verein and KBGS members we do our tests at or just before a year old and real work is being done alongside the shoe for success, the real tracks get harder with the experience of the dogs till they get to a level,regards wayne