The main difference is the tweeter and the crossover are upgraded in Statement version, but you still get the awesome midrange driver, the aluminum woofers, and the 3 passive radiators. This will give you the same amazingly deep and tuneful bass you get with the Statements. (Both models have the same frequency response specs.) Lastly, the Signature should be a good match with your electronics.
Highly recommended and Underwood is a great vendor to do business with!