Usability: If you’re a very mobile worker/student, or highly appreciate your cable free desk we’d recommend the 3.5. If the cable is not necessarily a bad thing we’d recommend the 3.0. In all other aspects they are the same.
Performance: exactly identical if both are USB connected.
Features and compatibility: The actual difference is the 3.5’s Bluetooth support and Android compatibility. The rest is the same. Both work with Windows and MAC OSX. They have identical scan speed and support the same font sizes.
Feel free to pop us a question.