I use a $20 cheap, aluminum pressure cooker that I purchased at a discount store about a year ago. I've also used a $150 pressure cooker/canner. Both have similar safety features, and do the job quite nicely.
The pressure cooker become dangerous only if the pressure inside the pot is trapped beyond the strengths of the materials used in its construction. My PC is made of aluminum, which I seasoned in the oven. The lid is of the same material, but unseasoned. The only way the device could fail is if I cooked something that clogged the pressure regulator. This is a simple device that is weighted to lift when the inside pressure of the vessel reaches 10 lbs. When it lifts, it allow a small amount of steam to escape through the valve it sits upon. This steam is vented though four holes in the weight (pressure regulator). If I were to boil some food that is frothy, or overfill the pot so that food, or starches could clog the valve, then the lid is made so that the gasket will push out long before dangerous pressures are reached, releasing the pressure. If that failed, then there is a pressed in safety valve that will litterlly pop out of the lid, opening a hole through which pressure can escape.
I don't think I could cause my PC to explode. If I were careless enough to exceed the safe cooking limits of the unit, the worst that could happen is that I could be burned by hot, escaping steam.
If used sensibly, pressure cookers are very safe, and extremely useful. Opening the lid on any of my pots could be as dangerous. Using my knife could be as dangerous. As with any tool, you have to be smarter than the tool. I don't think the PC is smarter than any of us.
As for your question, I would choose the Kuhn-Rikon. It's larger, has a steaming trivet, and convenient fill lines. Why would you need the extra pans, when you can fry/sear meats/veggies directly on the pan bottom, and then add the liquid as needed. You get the browning, and the flavor from the fond. Also, the Kuhn Rikon, to me, sounds like it would transfer heat more evenly with the sandwiched aluminum, rather than an aluminum base plate. To me, the bells and whistles of the more expensive PC just don't add up to serious advantages.
Seeeeeeya; Chief Longwind of the North