I don’t think you will get any recommendations against the 60CSx units. As you know, it really depends on your teaching and learning objectives. Garmins are great for learning basic GPS, navigation to waypoints, and field data collection techniques. However, you are limited to your data processing (no differential correction, I believe) and some of the more advanced data collection techniques (features within features, etc.).
At Smith we have both Garmins and higher end Trimbles. Thus, we have the option for simple direct instruction and use (Garmin) and more advanced GPS techniques for research and upper level classes (Trimble). Bear in mind that the Trimbles do require a lot of care and maintenance. The Garmins are grab and go!
We need to develop some open hardware GPS units!