Yes, you can try all the different varieties that you want. If you have any lingering questions about how much to feed so that your pup gets the proper nutrition, I would just call them or email them
Also, there's no reason why you can't give the different flavored Natural Balance or Canidae...They're supposed to be good for dogs with allergies, but there's no reason to think that they're not good for all dogs. They're all very healthy foods.
Here's a website where you can look up the different foods:
www.dogfoodanalysis.com
It gives you a thorough review of each food.