One of the advantages of a 6WD drivetrain is that with all three wheels on one side chained together, even if one or two loses contact, the total motor power can still be directed to the wheel that still has traction.
When the NEO came out, I did toy around with having a motor above each wheel in a 6WD chassis, but they were also all chained together: 6 NEO "outside-in", WCD, AWD drivetrain sketch