Thanks all for the replies!

I paid $954 all in for the ticket. The stay is over 30 days, and the outbound is at the the peak of the high season for South America (late December). As a result, the published fares are very high (over $1600) and unlikely to come down. Even very restricted consolidator fares are several hundred dollars more expensive. So in this case it's not just more flexible, but also substantially cheaper.

I'm not counting on the miles, but with the 1P bonus we're talking about close to 30K RDMs, and 14K EQMs, though half of those will be for 2005 and not very useful (already requalified for 1P and 1K is a looong shot). So it's nice to hear people keep getting miles on them .