The fact is that there is no need for actual pressure to be on that ball stack. Once the ball is in the breech, the hopper has accomplished it's mission and can relax. You only need to maintain constant tension 100% of the time if the hopper hardware isn't quick enough to react the gun firing. This is simply not the case with the Z2. When you are running around and not firing, the stack of balls above the breech are all staying where they are supposed to be, so you won't miss a shot. So mission accomplished.
For the next Z2 I'd like a smaller feed tray since maximum speed is no longer a priority, and lighter weight possibly as a result of a lighter weight motor.
Basically just as low and light as possible while holding 200+ balls. I'm eager to see what's next.