In my opinion, these recordings, far from being perfect (and I don't think I'm able to do any 'perfect' performance), have their shy moments. At least I tried something like this...
In the Pirilampos, I tried to take special care in three parts:
1) the introduction. It's easy to make it sound mechanical or uninteresting, and I wasn't satisfied with it. After some tries, I found out that it sounds better if I played the long notes a little longer (like a tenuto).
2) the middle forte section, finding a way not to slowdown too much, since I'd say it's nearly impossible to keep the 176 MM tempo while playing those chords and jumps, keeping the phrasing and emphasizing the theme in the bassline.
3) the final section, at 1'12. It sounded very strange when I first read this score. After thinking, I realized it should sound as an hesitation, so I tried to play this way.
(And I would say that I liked the contrast of dynamics I did in this passage, without using soft pedal. hehe)
4) the last notes. If not precisely played in tempo, it does not sound as a convincing end.
About the "volatility", you mean it should be faster and smoother?
not really... in fact, most of the time the dynamic marking is within mf and f.
The Nocturne is harder to bring off, musically speaking.
As it is too extended, I tried not to play so slow. But even so, I tried to make the phrases expressive (sorry if I'm not a very expressive pianist....
What bothers me is that middle section, but there is a consolation: the two recordings of this piece which I know, done by two professional pianists, have problems with this passage also.
In that passage, it's written CON FUOCO, and STREPITOSO in the octaves... Both recordings slowdown in the CON FUOCO (as I do also, since that's a small-scale Sorabji passage, hehe), and one of them plays the STREPITOSO too light and slow...