Large caps are not fast enough to help with the battery spikes caused during switching the fets. They help hold the voltage up, but our challenge with todays batteries and low turn motors is the switching which happens thousands of times per second. One of those cases where more is not always better and can be worse. It also must be close to the action, the fets. Caps hanging on 3" of wire are pretty much useless.
Smarter, Smaller, Faster....