I got to understand what you were saying, and i've been thinking about this too. It's always been annoying how if you are really tiny you jump pretty high and fast.
It is because of the datablock's mass. It goes something like.
Datablock mass * scale
Example: if you are a scale of 0.5 (small), then the mass of the datablock would be like 0.5 x datablock mass. That is why they jump high, because they are lightweight. Same with being big, you have more mass because you are bigger, so your jump isn't really that high.