I wouldn't think Iams would be particularly good for cats with sensitive stomachs, since it's not great quality food.

I used to feed iams until my boy started over grooming and the vet suggested it could be something in his food, once I started doing a little looking into it I was horrified I'd been feeding him such crap. Switched him over to JWB, over grooming stopped right away, now they're on applaws both wet and dry. Although I'd imagine if you've got that many cats raw would be a lot cheaper for you if you've the space and inclination.