>>3608138>You are not saying ANYTHING that does not equally apply to four wheeled vehicles.
Nope. The same theory applies, but what you're saying is like claiming that a three legged dog runs just as well.
>If the front wheels were almost at the center of mass then the slightest braking force would flip the vehicle.
You fail basic physics. In a braking situation, your center of mass wants to move ahead of your center of drag, which in this case means the combined forces of the gripping wheels. If the center of drag is the same as the center of mass, you have a labile situation - not stable or unstable but neutral. It can go either way.
When all your wheels are braking equally, the center of drag is at the middle of the triangle formed by the wheels. As long as this center is behind your center of mass, the vehicle is stable. If the rear wheel starts to slip, the center of drag moves suddenly forwards and the mass of the vehicle is now behind the center of drag. This is an unstable situation: if there is any difference in the braking forces between the two front wheels, the vehicle starts to turn around. If you lose grip in one wheel, the vehicle spins out at once.
The same would happen in a four-wheel vehicle, except you have one more rear wheel that keeps the rear from whipping out, so you have that much safety margin before you actually spin out. You have to lose 3 out of 4 corners to spin, whereas with a three wheeler you'll probably ditch it just by losing the rear wheel.