Knives have diminishing returns. IMO, a $30 knife is probably about twice as good as a a $15 dollar knife, but a $140 knife is not twice as good as a $70 knife. That isn't to say that the $140 isn't a lot nicer than the $70 knife, but it probably isn't twice as nice.

Is the RSK worth the price? If you can afford it, yes. The RSK has some pretty good blade steel, and Benchmade's Axis lock (which I really really like :)) But if you can't afford it you can't afford it. IMO Kershaw makes some pretty nice knives at some pretty good prices.