Ground mods may not be necessary on his board depending on how he did the ground traces. Gottlieb did it by running separate grounds for just about every function or driver group (actually the correct way to do power/wire harness designs). Of course, as the connections failed, problems showed up. If Swemmer or Ni-wumph has all the ground traces connected across the entire driver board, about the only place that I would think would benefit from addition grounding would be power supply to MPU and the MPU to Driverboard connections. So, grounding should be the same. You just have to determine what the ground trace is on each board (which I guess is what you are asking for?).

Certainly, the biggest benefit I see for the Swemmer boards is the use of the IDE style ribbon cable to replace the interconnect between the MPU and Driver PCBs. Of course, it seems unclear if this option exists yet unless he is making new versions of driver boards.