Yes, the main rotors are counter-rotating, that is why it needs the tilt-servos.
After I have slept a night on it I tend to use a BiCopter-mixing as it would allow for the main-rotors to spin more constantly instead of abruptly speeding up and down.
A coaxial drone is also on my list of things to build but i tend to make it variable pitch. Since the lower blades need to have a steeper pitch this will allow the flight controller to adjust the pitch ratio betwen the upper and lower blades automatically to max efficiency. All i will have to do manually is to vary the rotor size to find max efficiency.
A Y6 is very intriguing to me. The lack of efficiency should be fixable by finding the proper pitch. Does it fly well?