I have the 189 Hellbents and love them. I can't really compare to them to the other rockered skis out there because I haven't ridden them, but I did have 189 Maden's before so that's what I compare them to. They are awesome. Yes, they are soft, but since I got the 189 and can go 100mph and still be fine. They always land so solid. Even in soft snow, dropping cliffs is too easy. The tips just do not want to go under the snow. You can be leaning forward on your landning, and still ski away. And for switch landings they are even easier. I land 180s off cliffs so much more consistantly that I did with my Maden's. It really gives me a lot more confidence to just huck big switch landings into pow, and the skis just keep me from falling (well, most of the time).
Then for cruddy shit later in the day when it gets tracked out, they rock. You can fly down the mountain and run over anything. They charge a lot better than the Maden's. And I ski them in the park sometimes. They actually ski very well on hard pack. The shorter running surface makes them perform like short skis, regardless of the 189 length. With my Maden's I would get stuck on my edges and not be able to slide the skis around a lot, but none of that with these. Off jumps in the park they actually do get a good amount of pop, its weird.
For powder, I suggest a rockered ski hands down. Before I got my Hellebents I was very skeptical of the skis. You could go back and find posts on here from me probably bashing them for seeming like a stupid idea at the begining of the season. But wow. I was wrong.
I suggest the Hellebents out of those options. No on the Salomon for the reasons other stated above. I havent skied them, but the ARG's reverse sidecut stuff seems weird and unnecessary to me. The Pontoons would be a good choice, but only if you don't like going backwards, which is bad for me because I ski pow switch more than forwards.
Spark Notes version: Get the damn Hellbents, and thank me later.