Another question to ask yourself. How good is your fieldcraft and are you able to get closer without scaring the subject or falling into water etc.? If you can get closer, then it's a no brainer, if not, then it's a tough decision. I kept my 7D for the extra reach and will go to ISO 1600 (some scenes ISO 800), but I found that when I used the 5D MkIII in low light last October, the 7D never came out of the bag again for the rest of the week, because the image quality and AF was so much better. For travelling, the 5D MkIII certainly gives you more flexibility when travelling light.
Wait for Canon 7D2 or move on Canon 5D3?
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