I really like the Instinct Raw (never fed the bites, but it is the same formula as the rest, just a different shape!). I am not sure if you are re-hydrating the freeze dried, but if not, the Instinct is hands down going to be the better option. It also might be more compatible with the feeding of chicken necks (you want things that digest quickly, not sit in the stomach for a long time).
You could also do a mix of the Raw and Freeze dried, though I personally would only consider that if the freeze dried has water added to it. Consider also that the Instinct has some veggies in it, which are not needed for cats. If the freeze dried is purely meat, it might actually be the healthier option.
Lastly, I think the bison formula of the Instinct is not considered a complete diet for cats, so either mix that one with another complete diet, or avoid it.
Edit: Oh, and your kitty can start eating chicken necks whenever you want really. Just look out for constipation, and nothing without water or with grains should be fed with them (No kibble, grain heavy canned, etc). They also should not make up a large amount of the diet. Maybe once a week.
Last edited by Kytkattin; 11-04-2013 at 09:47 PM.