Re: two used roller furls - which one to buy?
You cannot add sections to the foil of the CDI. The foil is a single piece and is cut to fit the head stay. So the cost of a new foil will have to be factored into the deal. Also CDI makes several models based on size of boat and length of head stay, so you need to be sure which model it is. My CDI has performed faultlessly for over five years and I don't have to worry about corrosion at the joints of the foil, which is a big problem down here.
However, it would be nice to have a double sail track in the foil to facilitate sail changes.