The eco 500 is a new addition to the cfr range.I was told its a replacement for the cfr400.The guys at amtech were, i think, a little bit disappointed the 400 was discontinued!!.I'm not to sure of the difference's other then the size of pump, but it will perform very well.
If you've not owned a cfr in the past,then it can take a little time to get used to using.The recyclying feature dose work and you can achieve some very good results.Stick with using cfr cleaning products or Amtech approved and you shoudn't go far wrong.
The tooling is second to none.
good luck
joe