I'm kinda in the same boat too...I'm looking to move to Trimble RTK w/Autopilot in conjuction with current Insight monitors.  In addition to it's use in farm operations would love to use it with the tile plow (pull type).  Though I would love to control the plow, at minimum I would like the reciever to be able to provide an accurate topographic map to plan the system out (have a laser--just don't like using it).  Actually had hopes of gathering the elevation data while planting...is that feasible?  Anyway, I too have noticed used 214's for sale and wonder if they would do what I want (autopilot & drainage tasks).  Or would the 252 (popular around here) do what I want?  Whatever the case I love saving money to get the same results needed.  Thanks.