The 60csx looks like a nice unit, but I wonder how battery life is with a color display vs black & white. A color screen seems like overkill for a handheld unit.
While color is not essential, it does make a world of difference in ease of use. There's only so much you can do with 16 shades of grey and speed of mental assimilation of data is much faster with color.
There does not appear to be any significant penalty for color; after all an LCD is an LCD for the most part. I use a GPSMap 76c. It will run 3 times longer on half the batteries of my old monochrome 12XL. Now, most of that difference is in improvement in the processor and display technologies, but unless you are buying a low end unit, color is pretty much your only choice anyway.
I would be way more concerned about non-essential doodads that are being added by all manufacturers in the never-ending gadget race. All of them eat batteries without adding anything to navigation. Those would be the LED lights, walkie-talkie modes, barometers, thermometers, cameras, games (why do you need games on a GPS?), MP3 players, secret decoder rings and such.
I would recommend a high end model without all or most of those relatively useless features (and it may be getting harder to avoid them). Large internal memory and the ability to use a data card of some type are much more important. Why pay for another piece of hardware that essentially duplicates the current state of cell phone feature overload?
Since the manufacturers are continually releasing new models, look for a generation or two back (but still in production) and you should find some good bargains as those prices drop when the new ones hit the market.