I wondered the same thing. I went with the 60csx without question once I understood the differences.
I suppose the real choice will be how you use it since they are both good units.
I do a lot of long solo hikes and I map alot so the 60 was the clear choice for me.
here is the diffrences as I see it
much better display on the colorado although not as easy to see in the daylight and because you need to always use the backlight that eats up the battery faster on top of an already shorter battery life. I fond the colors dark on the colorado. Colorado does not have the declutter feature which I use all the time on the 60. The Colrado does have nice 3d and shading!
Colorado has a much larger memory, with that said I have almost never had any memory issues using a 4gig in the 60 (colorado allows for a 8gig)
Colorado is a better unit for geocaching as it has more features for that.
The controller on the colorado I found to be easier to control then the 60 although I find the 60 way easier to use overall with all the controls in one spot. Text on the colorado was a pain in the ass
The biggest differences show themselves after you become more familiar with the units. The 60 just flat out has WAY more features that I use often. For example, you can only display one saved tracklog on the colorado vs a dozen or so on the 60, route recalculation on the colorado is retarded, 60 can show distances between two way points, 60 can organize (show/delete) waypoints by symbol, The colorado does allow longer waypoint and POI names which is kinda nice, accuracy circle on the 60 is nice for geocaching (surprised the colorado does not have this?), colorado does not have night mode, Colorado cannot use the GPS features when plugged into a computer, and the list goes on.
They are both as accurate...I have heard that with equipment you can show the 60 is more accurate but as far as I could tell there was no real difference in accuracy.
In my opinon they are both really nice. each has a set of features the other doesn't. I say get the colorado for better display, more geochaching features and larger memory. Get the colorado for longer battery life, more functional in the field display, more features and overall higher usage, especially if you rely on the gps when out and about.
but...this is just my 2 cents