I'm not going to get into the hand catch debate. People have done it, do it, and will continue to do it. If it works for them that's pretty much the end of the discussion.
As for landings and roll overs, my perception has it happening most with newbies to the H in particular, and other multirotors in general. The higher it sits off the ground the greater the propensity to get rolled when landing. This isn't simply because of the length of the gear, it actually has more to do with pendulum effect, which longer gear accentuates. The real problem, IMO, is that newbs have yet to learn to deal with the sensitivity of the sticks when they are near center, and fail to realize that even tiny displacement of the sticks from the center position will cause the H to respond to a command input. They may not realize they are displacing one or both sticks slightly so when the H touches down it still has movement, or is trying to generate movement, in the lateral plane which causes it to roll.
Once the H is on the ground if the props have not reduced to idle mode they will still generate thrust. Any stick command will cause one or more props to speed up and others to slow down as the H tries to comply with the stick commands it is receiving, which in turn causes the H to tip. Many people do not understand that you are not done flying a multirotor until the propellers have stopped. The H is responding to commands received until the props stop turning.
I've rolled my share of multirotors, and every one was my fault because of inappropriate control input or attempting to land on a steep slope or uneven terrain. I rolled an H once, during initial flights, because of stick sensitivity but learned with that one event to keep the sticks centered after touchdown. There's also mention of how the throttle stick is released in a previous post. This is rather important because if one just lets go of the throttle stick from the fully depressed position before the motors have achieved idle the throttle will spring up and cause motor speed to increase. If not paying attention you may have the pitch/roll stick displaced a little so the H will obey those commands and use that throttle increase to make it happen. Then we have those that fly in strong winds, something I do frequently. When landing (take off too) you'll need to apply control input to counter the wind, and hold that input after landing to prevent the H from being blown over. If those control skills have not been developed, and multirotor newbs certainly have not, they will experience roll overs.
I'm not blaming operators per se, but I do tend to put the cause of the majority of roll overs on lack of experience and understanding, which does originate at the operator level. As skill level increases, roll overs decrease proportionately.
