Yes! our theories about these serekhs will remain uncertain for a long while I´m sure. We have to relay on conventions when searching for interpretations so at least we have some point to depart from and be able to go in various directions. Please allow me a bit of musing about H-rw here! :)

H-rw/Heru/Her/Horus is indeed, like the Narmer palette, (ca 3100 bc) connected to Nekhen if you look at its history, and personally I think much speaks for H-rw being a falcon deity. Thinking of how the ancients brought symbolism taken from the world around them (animals, water, earthly & heavenly phenomena etc), to work for them, a soaring falcon with its fast speed and penetrating eyes, hovering fearlessly seemingly close to the sun - such properties were likely to be connected to kingship. The depictions on sereks, seals, stone vessels etc, certainly bring your thoughts to a "falconlike bird" but it´s not until nearly 1000 years later that the so called Horus of Nekhen, ('the Nekheny'), the golden Horus head (ca 2300 bc) with two tall plumes, (I´m sure you know which one I mean), appeared. Just as Nekhen is called the oldest Egyptian city, that Horus head is called the oldest cult image found sofar. Now it is of course discussed if this head signifies the same H-rw as we see on serekhs, thinking of the long period of time which has elapsed since those Predynastic finds, but one thing is agreed upon - it represents a falcon. One would think that in a period of nearly a thousand years changes would occur. Ohyes when it comes to things which are not building or maintaining a society, but when it comes to deities and kingship it´s another matter. These sorts of things were there to preserve and uphold a hierarchical society - and what would serve better than a tradition maintained with religious means. As deities are per definition eternal, these are not very likely to be exchanged - even if a new ruling family came to power, it would probably be safer to assume that the deity most intimately connected and responsible for placing a ruler on the throne, would be taken on by a new family or dynasty. Then the next step could be to introduce one´s own family god on the scene if neccessary, once power was secured. We cannot prove this of course, so convention steps in; it is assumed that if Nekheny was an earlier deity, then by time it became assimilated into H-rw. And so H-rw continues to be connected to kingship from the early days and throughout Egyptian history. Quite a feat for a bird, hehe!