Installation took me less than 30 mins. On a scale of 1 to 10, with 10 being replacing the engine in your driveway, I would classify this as a 1. I have done many mods on other trucks and SUVs that we have owned in the last 25 years, and this was by far the easiest.
RE: potential energy - The weight of the vehicle does not rest on the links. By altering the length of the links, you are merely fooling the sensors that control the ride height. The stock links are made out of plastic, so you will be installing more robust hardware than those that came with the vehicle.
I installed a real lift kit on a 16 year old Avalanche last fall and that took us four hours. Three hours to figure out how to do the drivers side front and rear, and an hour to follow up for the passenger side. That kit actually carries the weight of the truck, and as you mentioned, I was reluctant to alter some components of the suspension, and I was somewhat cautious the first 100 miles. 4,000 miles later it is just fine.
As discussed in this thread, be sure that you pull the pin out of the stock link with needle nose pliers. The instructions suggest that you push it out with a screwdriver, and that is just not happening.
I say go for it.