Ive used these in Little Spinner. I started with the 20A versions and worked fine till I connected the disc to the motor. The Motor drew 23A starting current (connected directly to the battery) and with this MOSFET it overheated and shut down in less than half a second. It then pulsed as it cooled down and heated up so qucikly it was audiable. I replaced it with the 50A version and it worked fine from then on.

If you are wondering the heat sink was a solid ally block approx 10cm x 2cm x 2cm and it still overheated the MOSFET. The motor stall is not over 50A so in effect it should never hit this. I would not recommend using it in a PWM application unless its very low freq as its got a very long turn on/off time. I only use it in case of a short circuit in a on/off application.