Backpack for Rio to Lima trip

[ssg9]

Hi,

I am going on the Rio to lima trip in Jan 2013 and I am very undecided on the backpack that I need to carry. I will be spending some time in Patagonia ( 11 days as well) and trekking ..I will be carrying hiking boots and still deciding on what else to carry

http://www.gadventures.com/trips/rio-to ... SZRA/2013/

Anyone advice is appreciated.

Thanks
Seema