Cranberries in cat food ingredients? and Limited Ingredient diets?

I'm searching for a high quality grain-free dry food for my kitten but it seems like all of the 'top' brands such as Wellness, Blue Buffalo, Nature's Variety and Merrick have cranberries listed in the ingredients...is this actually ok for cats in moderation?  I've read that the benzoic acid from the cranberries is harmful to cats over time and numerous sources saying to avoid cranberry ingredients,  but then other sources say it has its benefits for cats.  I don't give a lot of dry food but I like her to have something to snack on while im at work during the day and overnight since she's nocturnal.  I plan on giving her Nutro grain-free Duck flavor as an adult (she's only 3.5 months right now and still needs kitten food)  but nutro only has the duck or salmon flavor so it would be nice to have a brand I can get that has other poultry flavors since I will not be feeding her any with fish.  Any one have any recommendations for both kitten and adult brands that fit my preferences?

The other question is- Is it normal/healthy to introduce a limited ingredients diet to a cat that so far does NOT have any actual food sensitivities or digestive issues?  These seem to be the only types of grain-free that don't have any controversial ingredients like cranberries or fish meal, ect but I don't know if there are drawbacks to introducing it to a healthy cat, especially since her other food is not limited ingredients.

Can you find Fromm in your area? I get it at Hollywood Feed. I get the grain free hasen duckenpfeffer and my cat Tuff loves it. First ingredients are rabbit, duck and turkey liver. No cranberries. I feed wet at mealtime and use Fromm at snack time. Hope this helps.

Many things are harmful to cats in the wrong quantity, including spinach, and tomatoes, which you will also find in lots of cat food. I think they must be adding cranberries because they are supposedly good for urinary issues, which may be true, I cannot attest either way.  I know that for certain health issues in cats, they are very bad.  

I don't guess there's anything WRONG with feeding a limited ingredient food now, but many people like to feed a variety of food, just in case of a recall, change in formula, etc.  That way their cats' don't get too used to just one thing and can adapt to change, if necessary

It doesn't look like they sell Fromm at any stores in my area unfortunately and it seems really pricey online.  I might have to "settle" for a not so perfect kitten food for the time being since there aren't too many different grain-free kitten formulas.  I think I'm going to go with the Whole Earth Farms kitten food, which unfortunately has chicken meal listed as the first ingredient and fresh chicken is listed after it, but it overall seems like the healthiest out of the choices for the now (no fish meal, no fruits, ect.), but if anyone else has other suggestions feel free to post.