Took my Tracker IV, Ace 250, Silver umax, and Compadre at a local school plot. Used the Tracker first, Ace second, Silver third, and saved Compadre last since it had least(?) depth. Tracker was in tone mode, Ace in Relics, Silver in min. disc. and Compadre iron nail reject. Tracker was good for first 3", Ace and Silver were about equally matched to 6" and the Compadre hit on all deep targets (large) that were left in the ground over 8". As expected from previous hunts, the Compadre found some 2-3" targets that were probably masked, one of them being a "soft sounding" quarter.. My conclusion: With all preset g/b machines, depth doesn't vary that much if you know your machine. Operator skill and being able to handle iron masking mattered. If you're not gonna get a machine with g/b capabilities-and can do without ID, might as well get the Compadre.