Hi Mark,
many, many thanks for the summary and for a very enjoyable post about Patek's silicone endeavours.
As you are mentioning it yourself in your section about the hair spring: these parts come out perfectly fitting, always.
That means that these parts do not need any further treatment, adjustment and labour that is coming from man.
I do not think that these parts are justifiable under the traditional way of making watches as they come out perfectly fitting.
However difficult it might be for them to come out in such condition it should still count for the manufacture to put all the effort into it and get a (mass) product that fits ad hoc.
The often mentioned fragility of silicone parts is very relative if you think of the anniversary WT moon phase and its two sapphire glass discs.
Let such a watch drop and the discs turn into star dust (pun intended).
I hope that this technology is only an addition to watchmaking and not the future way to manufacture watches as it would mean the death of traditional watchmaking.
Best
Moritz