Wow that is a good idea, and I think I will propose it to my little group tomorrow. I've been slowly building up my necromunda terrain, and it has steadily grown higher with multiple levels (as it should!) and we keep running into difficulty traversing between the levels quickly. The current jumping/falling rules are pretty restrictive.
How do you handle falling charges?
Also what is your opinion on horizontal jumping? The actual rulebook lacks two key words, 'up to', that changes the rules pretty significantly. The rulebook states you just go X inches, so you could overshoot your target. We play that you can go up to X inches, so you have more precision in your jumps.
I think this will go over well with my group.
Also, Lazura, your question about moving, falling, and moving is spot on. You can move all you want before you fall, but after you fall the only way you can move is if you fall less than 3" and roll a natural 1 on the dice. And don't think that all ground is hard, just imagine if they pass that test, they used the surrounding walls/ledges/pipes to control their fall. That's why there is an initiative test, to see how well your model can control the fall.