At one point I belonged to a detector club and one fellow with an M6 was pretty darned consistant at vacuuming coins up. I was impressed with him and that detector.
Almost bought an M-6 but the local Whites dealer was by appointment and he blew me off twice for an appointment after I drove half-an-hour to get there (burning up personal time to stretch my lunch break) and the second time sent his wife to wave coins glued to plastic paddles indoors. I got a bad taste for Whites, unfortunately, for no fault of the maufacturer and ended up with a used Minelab.