I guess I wanna toss in my opinion about the matter. Personally, I think the best judge of which Lot works best is in using the Zodiacal Releasing techniques as being revealed by Project Hindsight.
Apparently, the issue of switching the Lots even predates Ptolemy. It was supposed to be a technique put forth by Nechepso and Petosiris but the text was unclear and, much like the various interpretations of Ptolemy's system of primary directions, a slew conflicting opinions arose. By Ptomley's time however most astrologers settled into the habit of switching depending on the chart sect.
Part of the reasoning behind the switching of the lots must have something to do with the role of the dominant luminary. As I understand it, the dominant luminary (Sun by day, Moon by night) acts as one of the 'rulers of the chart', not quite the lord of the geniture but it has a role in determining the direction an individual takes in his or her life. Note what Rob Hand says again:
The Ancients said that The Part of Fortune was lunar in nature and The Part of Spirit was solar in nature, but they said something vastly more useful. Their descriptions stated in modern terms indicate that the Part of Fortune has to do with things that were unconscious, unintentional, instinctual, emotional and physical. These are all words for characteristics of material causes in living things. Whereas, the Part of Spirit was intentional, conscious, planned, ordered etc. It is the opposite. The implications of the ancient doctrines on the Part of Spirit and the Part of Fortune are that the Part of Fortune is a point of material cause in the chart and the Part of Spirit is a point having to do with manifest soul or consciousness, a formal cause.
In the Part of Fortune, the direction of native's soul is hidden. Hence the emphasis on unconscious events or more practically, events outside of the control of the native. Why? Because in the diurnal POF where Asc + Moon - Sun, the Sun is placed on the ascendant and the Moon's relative position is the active element. The Moon dominates in a day chart, the Sun dominates in the night chart. It is the suppression of the native's conscious will or perhaps its indirect manifestation which is represented by the non-dominant luminary of the chart.
In the Part of Spirit we have the reverse taking place. Now Asc + Sun - Moon in a day chart means that the Moon acts as an ascendant and the Sun is active element. The Sun acting in his own sect implies the point from which the native make decision of his own conscious effort and will. Unsuppressed and free to shine, the dominant luminary is free to act on its own accord.
This is now comes to the method of Zodiacal Releasing / Zodiacal Aphesis. The following two sites explain the details well:
http://www.projecthindsight.com/article ... 0Kerry.pdf
http://www.astrology-x-files.com/x-file ... hesis.html
Hindsight also offers a ridiculously expensive 10-hour lecture intensive on the usage of zodiacal releasing techniques on the prediction of the native's career. It is particularly important to note that the selection of which lot to use is based on the native's free will to choose his or her occupation. I'm no expert but in the charts that I've used the releasing techniques on, they make no sense without the flipped Part of Fortune and Spirit.
As an aside, the notion that the POF is the Part of the Moon and the POS is the Part of the Sun seems to be a later nickname that came about when Ptomely's influence stopped the switching of the parts. I don't believe the parts ever had those nicknames when it was common place to switch them.
Anyway, much of this hinges on the understanding that the dominant luminary has a specific role not given by the other luminary. If anyone has any further information on that, perhaps that may be the key to putting this age long dispute to rest.
Scorpion Eggs