I got Spencer at 9 months old from someone who didn't want him any more. His diet had been cheap kibble and cheap tinned food, his teeth were turning brown already.
His teeth are now white, his skin and coat are healthy and he's no longer hyperactive.
I don't really follow either Prey model or barf strictly, I feed a meal of liver every 2 weeks and other offal every other week but I don't worry too much about the percentage of bone to meat. The bulk of Spens diet is minced meat mixed with bone as that seems to be the preference here but he also gets ribs, fish heads, cows ears and a few other things so he's not just eating mush. He likes fruit and veg so he also gets those on a regular basis.