The S Mag motor is close to the most powerful mid drive motor by the numbers- dramatically peppier than most competing systems, with 15% more power than the already strong Brose T, It is more efficient, 15% smaller, and 11% lighter than the S Alu. The S Mag pushes 90nm of torque and 560 peak watts, and is applied with the signature Brose smooth/natural feeling and low noise/vibration. Specialized uses the S mag in their 2019 Levo eMtb bikes..
In terms of raw peak power, the Brose S is between the Bosch Performance (street) and top dog Bosch Performance CX (off road) motors - but that is only one part of the ebike performance equation. Torque (or the climbing grunt of a motor) is 20% higher with the Brose S over the CX. Total bike weight is a major factor (deriving from both battery, motor and frame supports), which is where the Brose S starts to really edge out the Bosch, particularly on the even lighter Mag S (Specialized 2.1) version. Anything under 50 lbs feels relatively light, but the real magic starts to happen once a powerful eBike gets down to 47 lbs or less.
Brose motors also kick in at lower cadence - you get more power at lower pedal RPMs than the Bosch, so the Brose feels more powerful off the line. There is also more assistance at the higher RPMs so you don’t feel the motor dropping off when you are pedaling all out.
Specialized uses the S Mag motor in the Levo, but calls it “Turbo 2.1” and there's an app that you can tune motor performance via bluetooth on your smartphone. You can connect to the Mission Control 2.0 app. Raw power is exhilarating and addictive - but full power all the time can also meaning depleting your battery very quickly, so judicious use of power is something eBikers value more over time. The app allows you to custom tune the assistance levels, or use “Smart Control” to algorithmically budget your power for you based on trip time or distance.