Browser diversity is a good thing. We've seen what happens when one huge monopoly dominates the browser landscape. Twice now, first with IE and then Chrome.
I use Orion because it's not a product of Apple or Google. There's no reason the browser should be a product of the same company who made the OS.
But it's not browser diversity in the sense people usually mean when they talk about IE and Chrome. It uses the same WebKit engine Safari uses.