Regarding "Slingshot"
I first heard it called a "Wenatchee Snatch" or a logging pick. It is basically used for loads that can be landed hard or are being picked at a higher altitude than the landing area, thus the pilot is planning (hoping) on having more power availble to stop the load at the bottom.
It is hard on just about everything. I firmly believe it is one reason that the Bell medium helicopters have such a dismal safety record when it comes to logging. Slipping. jolting loads are transmitted through the whole aircraft. Resulting in torque spikes to the power train. It does work, but it's way outside normal operations. I've done more than a few but no more. If I can reform any one can. And there is no reason for you to learn them other than to make an operator some money in the short term. Long term the additional maintenance will take care of the increased board foot or pound per hour profit.
It's best left to the old days because sooner or later it's going to get you or another pilot flying the machine.