I see the two as entirely different knives. The Para2 to me is the ultimate in light EDC. With the limited run in S90V and CTS-20CP, it truly deserves that title to say the least. The 0550 is an excellent hard use knife with buttery smooth opening, a solid lock up, and a beefy handle. Ergonomics of both are excellent, but I like my 0551 better because of how it fits in my hands.
Ideally, I carry both my 0551 and my Para2 in S90V and Carbon Fiber. One for hard use, one for light cutting(and eating up cardboard). It depends what you intend to use them for. The Para2 is excellent so long as you don't try to stab it through a car door, pry, chop, or baton with it. The 0550 would be able to handle the above tasks better.
To be honest though, you might as well go for the 0550 unless you're picking up the Para2 sprint runs. From a performance standpoint, I'd expect Vanax35 and Elmax to outperform S30V, if only by a small margin. But S90V and CTS-20CP(the sprint run steels) would be on top for edge retention(with a tradeoff on toughness).
In the end, it depends what you intend to use the knives for.