I am also trying decide between the two. According to the recent gpstracklog review on Oregon 450 , the 450 is as good as 60CSX in terms of accuracy. And right now the two are in similar price range, the 450 just seems to be a better deal because of the better features. The custom map feature on 450, which is missing on the 60CSX, is really nice and useful. But the 60CSX does have better battery life and screen reading in sunlight.
Another option is the soon-to-be released Delorme PN-60. But it is a little bit more expensive.