whoever said they did the physics...i call bullshit. If you wanted to do that right you would need a lot more info. The picture offtrail posted had the table length and landing length.
For simon's, you would need the takeoff height and angle, the landing height and angle, dumont's weight, and speed going into the jump. Pretty much the same for tanner's situation. That would still only give you a rough estimate of the amount of force they hit with, and I'm sure their position when they land factors into it. Basically there's so many factors that comparing with physics is kind of pointless.
How about the risks of each? My guess is that dumont was way closer to death, especially from a concussion or something involving his spine had he landed differently. On the other hand, if Tanner got a bad compound fracture of something like his femur, he could have bled to death before getting off the mountain.
I definitely disagree with anyone comparing based on who healed faster. My fractured wrist took 6 months and a surgery to heal. If I had a clean break in my forearm instead, it would have been like 6 weeks in a cast and done. Which sounds worse though, broken arm? or fractured wrist.
In the end, both were horrible crashes, and shoul remind you that at the highest level, skiing and boarding can be extremely dangerous. Pros are so practiced that stuff like that doesn't happen much, but the chance is always there.