[Mike Martus]

The problem you describe has several issues to consider.

While there is some fact that motors running in reverse are not as efficient the difference is usually not measurable.

The cutting out of the motors is usually the auto reset breaker tripping. What you need to investigate is WHY is the breaker tripping.

Breakers trip when the circuit draws a load greater than its rating. In your case it is 30 amps.

I would suggest that you look close at the following:

Drag / friction on your drive system
Alignment of sprockets
Load on motor - Are you trying to drive four wheels one on each corner and "Scrub" turn causing the breaker to trip?

If the breaker is tripping at start - Full joystick throttle - you need to look to the gear ratio. Example: What happens if you try to take off from a light in your manual transmission car and you forget you are in 3rd gear? There is a balance between speed and power .... you cannot have both with a single gear transmission ratio (DeWalt). If the breaker trips when you are trying to turn..... it is usually the gear ratio and the amount of "Drive Friction"... in other words you are asking the motors to do to much work.

The back drive issue is due to the transmissions still having the "Pins" in place. You will want them, removed for Dewalts used on a drive system.
If you do not understand how to do this download the White paper " Nothing But Dewalts" found on this site.