I just did my first test drop. 10 dwarven volunteers were dropped 19 z-levels. I meant for it to be 20, but miscounted. oops. And actually there were 10 volunteers, plus one baby. Before the falling damage was changed, this height would have been 100% fatal, with everyone fully disassembling upon impact. This is no longer the case.
I watched the fall one tick a ta time, and it was very interesting. Dwarves fall at a wide variety of rates. The baby parted company with mom immediately, and fell faster than any of the other dwarves. It hit bottom after 37 ticks. The next dwarf landed at 40 ticks, and the last one didn't hit until 57 ticks. There were also 2 mid-air collisions, one of which resulted in death.
The first mid-air seems to have been due to two dwarves starting in the same tile. One fell slightly faster and ended up at -6 z-levels while the other was still at -5. Then the next tick the second dwarf dropped to -6 and collided with the first, who was still there. One dwarf took damage and the other didn't, but I'm not sure which was the one that was already there. The one that took damage did slow down a lot and ended up being the last one to land. He took 5 hits, including a broken bone, 3 bruises (including a lung), and spinal damage that would have been enough to be fatal, even if he hadn't smashed into the bottom of the test chamber a little while later.
The second mid-air collision didn't seem to involve two dwarves. The dwarf that has hurt was next to a wall, and may have just hit it. This fellow took 6 hits, 2 broken bones, 3 bruises (also including a lung), and a smashed skull driven into his brain. So in this case, it was the fall that killed him, he was already dead when he got to the sudden stop at the end.
Of the 10 who fell, 3 were dead immediately, 1 died shortly afterwards from suffocation, 4 are in the hospital, 2 landed on others and only got stunned and walked away unwounded. The Baby has both arms and both legs broken, but nobody has bothered to do anything to help it, so it's dragging itself out of the test chamber, leaving a trail of blood. Its mother is dead from the fall, and it's father is ecstatic, despite (or maybe because of?) his wife's death. He wasn't in the test group, BTW. Maybe that's why he's so happy.
Of those who were alive when they hit the bottom, they each received 6-9 hits.
Oh, look. One of the two that walked away unharmed just went berzerk because 4 of her friends just died. I guess I'd better go deal with her.
I'll do more tests later from greater heights to see if there is a height that is reliably fatal.
TL;DR: falls from 19 z-levels are no longer automatic kills. Only 40% of my test group died, with another 40% hospitalized, and 20% unharmed due to landing on others.