Read the ad again. It includes the control board at the introductory price. They look like just a reworked version of the 615 design, which in my opinion is a weak design, the little teeth on the gear need to mesh perfectly with the side rails and when you put any side force on them they pop out of place. I would want to know what the weight would be with the struts. Since the Sierra gear include the struts in the price all things equal they are the same price and function flawlessly. If you add the weight of the gear + stuts + battery for the Robarts, I would bet you're not far off in the weight category. I don't see the issue with the weight of the Sierras, both my TF Mustang and P-40 weigh in at 11 lbs and fly and land with out any issues other than the 615's collapsing on the P-40 which was solved by going to the sierra gear.
