You pretty much answered your own question, but I'll break it down as I understand it.
Stiff park skis are better for bigger jumps and tend to be more stable.
Stiff pow skis are more stable for charging and sending bigger cliffs
Softer park skis are better for jibs, butters, etc
Softer pow skis are better for playing in the pow, many pow skis are fairly soft.
I prefer medium soft skis, I don't tend to send it too big, but love to play around on rails, do butters, and smaller jumps. Pro's are just going to ski whatever their sponsor gives them unless they have some input into the production of the skis.
Confidence is the feeling you have before you fully understand the situation.