Well really a slight change of mind. I have made two changes to the last sub-section (1.3.3. Gravity). The first was I wasn't happy with my humming harmonies and so with a stroke of typical genius (and modesty) I have instead substituted some mellotron playing. Much better.
The second was a couple of concerns about the ending, having listened to it. There is a low humming which comes in and lasts up until the backwards cymbals. At the front of the whole track it is fine, but here, backwards as the outro it felt like there was a little bit too much of a gap between the fade of the hum and the cymbals. Also the hum is an E note, while this section is in D. Really the hum needed a couple of changes.
Option 1: pitch-shift the audio to take it down a tone, easily done, but doesn't fix the gap.
Option 2: same as above, but add a bit of the same sound in to cover the gap
Option 3: rerecord the first section without the hum, and superimpose the hum at the right pitch
And the winner: option 4: make temporary changes to the first sub-section, lowering the hum and bringing it in slightly earlier especially for this ending.
Something that appeals to my slightly twisted sense of humour is that this ending still sounds like it is the intro backwards, but you would have to be pretty observant to realise that it is different from the actual intro.