I vaguely remember reading somewhere that the reason for the empty "neutral" between 2nd and 3rd on the old hubs was that they had to do this to absolutely prevent 2nd and 3rd both getting engaged - the hub instantly self-destructed if this happened.
Regarding the planet pinion axles, I have always thought that making the pins with a slight widening taper on those ends, with a matching angle on the clutch, would solve the problem of accidental disengagement. (Actually perhaps I read that in one of Brandt's posts as well.) Perhaps this is what Sunrace SA did.
I am guessing the additional pawls are for eliminating the neutral, so that even if it disengages, it doesn't cost the rider their b*lls.
I am sure that the change in shape of the planet axle pins is to do with ensuring better engagement, and maybe they are tapered outward by a thou or two. I didn't examine them that carefully, only noting that they are radically different in shape to the old AW ones. The other thing to say is that the driving of the ring gear in first and second gear is different to the way it was done in the old hubs, since that drive is engaged by the new set of pawls on the driver operating inside the right hand end of the ring gear on a new set of dogs. These pawls can be engaged and disengaged by the cross shaped clutch assembly that slides inside the driver and the ring gear. The other possibility of difference in top gear engagement would be the shape of the dogs on the left hand face of the clutch that engages with the planet axle pins. In fact the clutches and drivers on the old and new AW hubs are entirely different. On the old aw the clutch is just a simple metal cross whereas the new one is much larger and more complex. The old AW driver has a male style of engagement with the clutch, whereas the new one is essentially the opposite. It is worthwhile looking at the Hadland old AW clutch and driver diagrams alongside the New sunrace NIG ones. The differences are pretty significant.