Some really good points brought up here. How are they going to keep mechanicals as well as strings and cables together is my biggest question. As per usual, manufacturers are ahead of material constraints and will worry about them when they pop up. I guessing at 500 ft/sec fixed broadheads will be problematic.
One thing that struck a cord in me is my survival instincts will tell me not to shoot the R18. I already creeps me out to shoot any compound bow because of the fact that the cams are being pulled back and want to come back towards the shooter. In the R18's case, they are pointed towards the shooters face. What will happen if there is a catastrophic limb failure? I think the movement of the limbs is going to be very distracting on the shot.
Ravin is definitely doing some good thinking outside of the box, I just hope they've done more thinking than they have in the past.