I would like to travel from Miami to Montevideo/Buenos Aires, then on to Sydney and eastern Australia, and return in Feb 09.

A simple price search on EF gives me a DONE3 purchased in MIA for $8600. However, if I fly down to CCS to begin my journey there, a DCIR29SA can be purchased in Venezuela (yes, I have access to a TA in CCS) for only $8000 (not including currency discount). It seems like a no brainer, am I missing something?

A simple CCS-MIA-xMVD/EZE-SYD-xBNE-xCNS-xHKG-LAX-MIA routing puts me in at 27.5k miles. a) Is that a valid DCIR29 routing, and b) Would I be required to ticket all the way through to finish in CCS, or do I just have to start there? Yeah, I know I can throw away the last segment, but that puts me up against the 29k limit and no room for additional flights within Oz if I'd like.

For an extra $400, what's the advantage of a DONE4 over the DCIR29?