I used to use two of the hard drive based portable card "dumpers" (X-Drive was the original, now there are a few)
I used two as I did not like the idea of having one copy on a hard drive in rough conditions, so I copied each card to BOTH (poor mans RAID )
However IMHO the usefulness of these "card dumpers" has worn off.
Cards are much larger and cheaper, and as pointed out, a netbook is also in many cases cheaper, and clearly more flexible.
I now just carry enough cards to do the job,.. it's lighter, no charger, no time needed to transfer, etc. (FYI did Galapagos last year, and just got back from Machu Picchu!!! Have fun!)
Especially on the Galapagos trip, I would have been hard pressed to fit card transfers into the tight schedule without it being a panicky event. (there is time, but none I would want to sacrifice. )
I'd suggest either get enough cards, or go the net book route, and also bring a USB external and mirror the photos to both internal and external drive..