I too agree that we are close to the ideal equation for traction. The main reason for the wider wheels on my drivetrain is for the reduced tread wear not for increased traction. I would like to not have to change treads frequently so that is where the 1.5" width came from. Also yes if the game does not include much climbing or if the object to be climbed is not particularly steep then a 6wd layout will most likely be used.
One thing about this particular design is that the overall weight gain from adding 2 extra wheels is not particularly large (>3lbs) and the drivetrain has an inherent cool factor. If we have the extra weight, the cool factor certainly outweighs anything else
assuming all things else are equal. Im confident we can run 2 extra chains and wheels without a problem. Something about laser cutting everything tends to have everything line up perfectly.