I would go with the 6GB Kit DDR3 2000 G.Skill-Trident.
The Corsiar RAM is a well known, respected brand, but it's slightly slower, and to be honest, I never to this day had any RAM fail on me (call me lucky).
Considering all that said, just purchase the one that comes cheaper. You won't regret either choice. (I know I recommended the Dominator's in the first place. )
Depends on which has the lower latency; I'd go with lower latency over higher frequency, provided the price difference is not too large and both come with good heatspreaders.