I've been feeding the Tiki Puka and the Koolina since April and very satisfied with both. Occasionally - Tiki Wild Salmon.
My cat likes FF Liver and Chicken Pate but I try to give it to her only when the money is tight as liver in the cat's diet should not exceed 1/5 of the total ratio. I use Friskies Pate - high-ish carbs/ HIGH P for my girls when her BG numbers are lowering.
But you are right both the FF and Friskies are high in P. The best food with respect to low P content is home made raw or semi raw. Have you read Dr. Pierson's?
Here is the link.
I never used Iams so I do not know. I might be mistaken but I think at the moment that Iams products were compromised somehow, I cannot remember the details... If you get a chance search this entire site for "Iams" - I bet there was something bad posted about its products a while ago.. Again, I might be mistaken!
I shop by Dr. Lisa chart - and I couldn't find any lower P content than in the Tiki Cat so far (at least available in So California).