So here's a question that's easy to intuit but hard to define: At what point exactly does a short girl become a Little Person and a tall girl become a Giantess? Extrapolating further, at what point does a Little Person become a Minigirl and a Giantess become a Macrogirl?
Also; where do you personally draw the line regarding the extent of extreme size differences between partners before it gets to the point of ridiculousness and unfeasibility?