Missing Link is a great product, BUT if you are happy with the results you are getting now, I wouldn't suggest switching.
The main reason I don't use Missing Link is because it is primarily flax seed. Not all dogs handle flax seed well, and IMO animal-based Omega 3 sources, like fish oil, are superior to plant ones (for dogs at least).
Second, if you were just looking to save money, and your dog does fine on flax, it is much cheaper to buy bulk flax seed at the market and grind it yourself in a coffee grinder. You have the added benefit that you can grind fresh daily providing a healthier source of flax oil than what Missing Link can.