You caught be at a bad time yesterday. i could go into a big long tirade about how to short rope but the reality is that it is neither easy or hard. I hear people like yourselves try to make it into a big deal. What are you really doing with the rope. Hold on let me answer that since you'd just throw out some made up numbers. By the way those numbers you threw out are exactly that they are made up because they can not be applied. This is what so called rescue experts do to make themselves look smart in front of their students by throwing numbers about.
The primary purpose of short roping is
give the clients confidence
direct them away from the potential hazard
setting a pace
monitoring their over all well being
preventing a stumble from becoming a fall

Nothing about this requires extensive training. In fact we have plenty of 20 years plus veteran guides here in the Rockies that couldn't short rope to save their lives let alone anybody else's. Sure the same holds true for many other countries. I guess it's part of the smoke and mirrors on the guides side to make everybody think this is some big deal and it isn't. keep the kids roped in direct them away from the edge when you see the problem about to happen ( the trail narrows for example) Does it really sound like a hard thing to do. Course now you can throw out some more useless numbers (which by the way folks there is no way to generate any real data on forces applied in a short roping scenario)
Besides which I'd rather be tied in with my kids cause if one of them died I don't think I would want to live anyhow. Besides from the trail description you have a better chance of losing a kid from a random shooter in their elementary class.