The only reason to go for 2GB is that either you're strapped for cash or you're upgrading an existing machine. In which case this kit of twin modules is for you.
With quoted timings of 5-5-5-15, it was a relief to find these functioning just fine in the same system at the full 8,500MB/s bandwidth.
That said, the extra RAM speed it has on some of its peers made very little difference.
The G.Skill spreaders aren't as snazzy as many of their competitors, but are up to the job unless you're going in for a ludicrous overclock.
Right now they provide stability if you're overclocking a rig where the FSB:Memory speed ratio is locked (ie. an Intel chipset), but for a new build 4GB of PC2-6400 will fare you just as well for games.