There are lots of ESCs that use SMT FETs without heatsink tabs. They use low resistance FETs and thick copper traces on the board to dissipate the heat.

Otherwise the board looks pretty similar to the other boards. Perhaps they redesigned the board to have the option of installing bigger FETs on the daughter board when needed, or to use connectors to make them easier to install in the tanks.
Pity, had been hoping that it might have signaled a redesign capable of a battle system.

D.