There is no substantial difference between a Cover 2 and a Tampa 2. Dungy, Lovie, Marinelli all coached at Tampa and when they left, they simply changed the name to a Cover 2. Dungy said he copied the defense from Chuck Noll's Pittsburgh's team and I'm guessing he saw no reason after he left Tampa to continue to call it by that name. Lovie Smith and Marinelli followed suit. Each team that plays a Cover 2 has a few different wrinkles but in essense, It is exactly the same defense.
Every defense has its strengths and weaknesses but Tampa and Indy have won the Super Bowl playing it and Chicago at least got to the Super Bowl using that system.
Every system of defense is effective if you have the personnel to run it, if you don't have the proper personnel then every defenses weaknesses can be exposed.
The Colts as mentioned won the Super Bowl using a Cover 2, New England and Pittsburgh using a 3-4 won a Super Bowl and the Giants using a basic 4-3 won a Super Bowl so it really doesn't matter which defense you use, each can bring you a Super Bowl victory if you have great personnel.