I'm not sure what you mean by a cooked diet with added supplements? Do you mean commercial raw diets (as opposed to preparing raw at home)? If so, I'm pretty new to raw as well, but I've tried two brands of commercial raw: Nature's Variety Instinct and Answers. My holistic vet strongly believes that it would make a huge difference for my 17-year-old kitty with early CKD and arthritis in a couple of joints. He'd tell you that a raw diet is beneficial for virtually every medical condition, and I think many forum members would agree. He also highly recommended raw goat's milk.
My kitty was on a half wet, half dry diet for most of her life. I finally managed to switch her over to all wet about 2 years ago, after a 2-3 year battle. A couple of months ago, I did a very slow introduction of the raw, mixing just a little into her wet food. She totally loved it at first, then when I got to about a 50-50 mix, she decided she was done with it. Same with the goat's milk. So I backed off and retried just a teeny bit of a different brand and flavor. She ate it, but unfortunately, I noticed that the expiration date had passed (!!) so had to throw it out and my store didn't have more.
Because my local store has such limited options, I'm about to check into companies that would deliver. If I find any info, I'll post here.
I hope doodlebug, one of the mods, will be by here to give you some specific recommendations. She knows a lot about foods and raw in particular, and also has experience with IBS.