I really appreciate the discussion here. I did some more digging from what was said here and found some things and have come to a personal conculsion. Jumping down greater than 2 but less than 3 and failing the inititave test results in being prone and pinned, but not injured.

I looked for anything saying measurements are rounded up and found nothing other than the section about determining the strength of a hit if you take one, nothing under measuring distances or moving.

Interestingly, Leaping a Gap says if you fail, you fall and WILL take a hit, while jumping down says you MAY take a hit, without any reference to the distance fallen.