[Joe Johnson]

One thing to consider when doing FWD with 1 motor per wheel rather then 2 motors + 1 chain per two wheels is that in the 1 motor per 1 wheel case you are depending on both wheels being on the ground to get both motors to do useful work.

If, for example, someone rocks your robot back on its rear wheels, you will not be able to get the benefit of having the motor driving the wheel that is in the air. This is not the case when you have 2 motor + 1 chain driving 2 wheels, in this case, the power is automatically transferred to the wheel that remains on the ground.

Is this a definitive answer. No, of course not. There are 100's or reasons to go this way or that with a FIRST robot design. You have to balance what you save in weight, complexity, and (often times more important) package space against the things you like but give up.

Welcome to the imperfect world of design!

Joe J.