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.