I presently keep 4.5 couperi from 4 different breeders. 2.2 are 2006 animals, 1.1 are 2007 animals, and 1.2 are 2008 animals. My older indy's show this behavior you speak of, however when they were younger you had to ration them for they would eat until they bursted, as do my younger ones now. So, in my experience it seems to be age related regardless of genetics.

Tim