On the hand, offering a wide variety of concession items can provide something for everybody.
However, by providing too many items, it will start to decrease the sales of certain items. So if you have a wide selection of pop, frozen drinks, and bottle drinks, you are bound to lose sales in a couple of flavors.
Another thing to consider too is if you have too many items for customers to choose from, it will take them that much longer to make up there minds. I know that if you have more than one of a particular item and ask the customer what they want, they have to ponder what they want and it can slow down the concession lines.
However, it does not hurt to at least try out these products to see how they will do in your theater. If nothing else, if they do not sell well, you will just not have to get anymore of them. Otherwise, if they sell well, you can keep ordering it. Anyway, let us know what you decide to do.