That brings up another point; more pushing force also means you need an ESC with a higher current rating and batteries with more capacity. Its really tricky to get the whole drive-train balanced so everything matches with no weak points.

I noticed that the magnets on NST are mounted in little pods outside the frame, so you can definitely use that with a steel chassis. I also like the idea of using less powerful magnets to correct weight imbalances and to make a bot drive better. All my bots have too much weight over the front and less over the wheels. If I could add some magnets near the wheels, there would be more down-force where its really needed.