Absolutely, the System Sensor 2351B is a significant upgrade over the 1251B. While both detectors serve the same purpose, the 2351B offers enhanced features such as improved sensitivity to smoke particles, better false alarm immunity, and compatibility with newer fire alarm control panels. Additionally, it boasts a sleeker design and easier installation process, making it a preferred choice for upgrading older systems. Overall, the 2351B provides superior performance and reliability compared to its predecessor.