I think I'm ready to start the final illustration. Flipping the child's figure has given him more movement, you can start to feel the sense of rushing air. Reducing the size of the figure in the composition gives him space to 'fall' into and emphasises his smallness and vulnerability.
Also, flipping the image makes me look at it again afresh and tends to show up all the proportions that are not quite right. I often hold my artwork up to a mirror for this very reason. Accordingly, I've made a few tweaks when drawing out the final artwork, which I'll post soon.