Not really a secret, but knoledge and work. About vibrations on board, maybe you miss this: viewtopic.php?f=24&t=2990 . I strongly recomends you to read it and apply to your designs. It´s the starting point.
For power distribution I use my own central plates in carbon WITHOUT any power distribution lines. I joint all power lines in the center of the plate stacked in a fully symetric way (see file attached with images).
Respect the landing gear, It´s up to you to design a "stronger" system. In any flying machine, there is nothing better than other, but simply that fullfills the requirement or not. Otherwise is "dead weight" that you´ll keep onboard forever.
A servo working while keeping a clamping force will draw important current and also introduce vibrations and noise (I tested that). Also it can be burned with use along time. Of course you can use big servos like in RC sailing boats, but this is other history.
So, in my own experience with many flights now with this latest landing design I find it simple, cheap and robust and makes the work perfectly with payloads, let say, around 1 Kg. In a real helicopter it´s not expected to land at more than 1m/s, as I guess you´ll try in your heavy copter.
The bottom line It´s simple: to protect against potential crashes means weigth on board.
Thanks for your interest in my designs and keep tuned...