I'm new to geocaching and this forum but not to GPS technology.
I just purchased my first recreational grade receiver and didn't get the 60CSx, even though a very experienced geocaching friend said he wouldn't have anything else. Short answer is the more expensive product I first bought was disappointing.. reboots, failure to acquire satellite fixes in good conditions, very poor WAAS reception.
Ran as fast as I could to REI and bought the 60CSx and lo and behold, I am a happy cacher. In side by side tests it would regularly track and lock double the sats (at least according to the displays on the respective units), and is rarely without WAAS reception. Large screen, easy to read, excellent performance under canopy.
The 60 has an older-looking user interface as compared to the newer Garmins (if that is important to you), doesn't have the bells and whistles of say the Oregon 550 (paperless caching), but for me accuracy and performance under less than optimal conditions (canopy, poor sat geometry) are the most important, and for that I am sticking with the 60CSx. I did score one with the Sirf III chipset @ REI, so they are still out there. I have no experience with the Mediatek chip.
So, 60CSx and the topos from gpsfiledepot and I am good to go.