Version 6 bug: In both Giantess and Gluttony paths, the descriptions for gain stages 7 and 8 are identical on all 4 body types. This also seems to apply regardless of height as well (didn't test average height).
Hopefully some of the other paths that are currently more limited get built upon (like the cave route). And the water inflation scene seems like it should add a gain stage as well.
EDIT: Oh, something else I thought of, being a Dragon should make "jumping the hole" in the spaceship before the final two growth stages possible due to the wings.