Maaaan, that is some dope idea, but the fact I can't figure how to use the Bonus cog and the Collect area just bothers me! I managed to open the gate, but I can't do anything else... I also managed to start spinning the Bonus cog, and even attached the Drive with the arrow to the collect, nothing worked...
Also, I faced a bug, not so sure that this is the proper way to reproduce it, but what I did is: placed the Small cog(8T) inside of the Motor-Bonus-Collect triangle, placed a Drive faced to the Collect area, connected them with the chains: Motor->Small Cog->Drive->Small Cog near the Bonus to make it spin. This didn't work, and I used the Right Mouse Button to take all parts back and receive the gold, but after I erased all details - I only received 200g instead of 400g.
Overall a great idea, but needs some polish+tutorial!