There is a new one on the market the unequalnox 600. As four modes: Sticks, balls, cat poop and small dead animals. There is rumors of the yet to be released 800 that will tell you the sizes of the sticks and balls, what type of cat made the poop and can even tell between dead chipmunks and squirrels (kind of hard) and possums, birds (a no brainer). It can be adjusted to find flattened squirrels, decomposed squirrels (the best to roll in) and freshly killed squirrels. But most dogs seem to prefer XP Sayus which has been proven in the fields, marshes and creeks and recommended by the Hunting Dogs Association of America. Neither the Unequalnox series or XP Sayus works well in the winter time, something to do with freezing temperatures not carrying the pheromones as well as in the hot summer. There is no such thing anymore as a field that has been hunted out by other hunting dogs. Rest assured they missed some juicy morsel that the 600 will find.
The large unequalnox dealers are quoting a six month waiting list for their 800's on backorder from Findlab detectors.
(note: I own an Equinox 800 and love it, just poking fun at friendly differences of opinions on the Friendly Metal Detector Forum.)