I haven't personally witnessed many of the truly truly deep deep game dogs. Seen a few.
Here's on of the family of dogs I like to feed. His name was Lucan and his tombstone reads, "If any dog can, Lucan".

He went over 2 hours with no turns and no holds. Extremely game dog. Acted like a puppy dog in person. Not real strong in the back end (like some Alligator dogs come) but man, smart smart smart and near Ace. I've got a couple of dogs with him on top and bottom and he and just a few others are dogs I like to focus on. Much like Jack around Hammer/Poncho stuff.

http://www.thepitbullbible.com/forum...p?dog_id=11216