I've seen a couple of dual motor and dual engine setups. No doubt that when setup right, they perform very well, but never as well as you'd hope they would. Of course, I haven't seen/done everything. I'd love to be proven wrong. It would give me an excuse to venture into a place that I've never, personally, been before.

The real downside is the return on investment. Figure two MM systems at about $400. For the price of a MM esc and Feigao motor, you could still have money left over for a lipo pack and it will probably run as fast or faster than the dual motor setup.

Again, I'd really love to be proven wrong.