I'm still wondering what the argument can tell us about Sextus' conception of the privacy of pain (not much, I think, but it does suggest that he would not reach for the sort of explanations of the privacy of pain which occur very readily to modern philosophers of mind and that itself might be interesting). But I'm also wondering about the legacy of this argument in later theology. It's clear that there are arguments over the possible compatibility of omniscience and other sorts of perfection. For example, we might compare this thought with a concern raised by Richard Francks, which he relates to a demand to ascribe to god omniscience ‘in a strong sense’:
‘My knee hurts, and I am aware of the fact. If a perfect physiologist examined my knee he would know it too. But there is a difference between my awareness and his. What kind of difference? I do not know anything which he does not know. On the contrary, he knows much more about my pain than I do-'I only know it hurts'. I do not even want to say that I know it better than he does. And, provided he is giving me his full attention, I do not want to say either that I am better aware of my pain than he is. ut there is still a difference between me and him: we know what we know in completely different ways. We might say: we know the same thing from different points of view. The question then is: is it enough for God to be the perfect physiologist, or must he somehow 'feel my pain'? I think he must, because if not, then there is something which I know and he does not, viz. not my pain, but my view of my pain. Of course, God 'knows just how I feel', but that phrase is no more comfort here than elsewhere: his knowledge remains theoretical, derived, whereas mine is perceptual, immediate. Mine is not therefore better, but it is different. If God's knowledge of my pain is only that of the perfect physiologist, then I have an awareness, a perspective, which God lacks. And that contradicts the spirit of the first requirement.’ 
Franck’s reaction to the argument, as far as I understand it, is that god’s omniscience can be preserved by god’s immanent omnipresence: god does have my perspective on my pain because he is ‘in me’ and therefore can know it as I can, ‘from the inside’ as it were. (I wonder what a Stoic would make of that.) I have also found some other discussions of problems raised by the tension between divine omniscience and experiential knowledge, particularly of pain, in Sarot 1992, 70–77. 
 Francks, R. 1979. ‘Omniscience, omnipotence, and pantheism’. Philosophy 54: 395–9, at 396.
 Sarot, M. 1992. God, passibility and corporeality. Leuven