The 150A uses 36 MOSFETs, ON semi's NTMFS4833N(the MMM uses NTMFS4108N).
Here's my picture.
On the top side of PCB: 4x6 = 24 FETs，there are two more rows underneath the power PCB, 2x6 = 12 FETs. Note the way the heatsink touches. Looks like HobbyWing was trying to cool the PCB, not directly the FETs (to take care of the ones on back side maybe? ).
