My last holiday, I went to Macau, HK, and Thailand. I brought almost all of my gear. There were times where I went out on an excursion or a walk and just took the 500D instead of my 5D3. However, thinking about it after I had gotten back home, I probably should have just left the 500D at home and carried around less gear. The 5D3 alone would have been fine. Just because you CAN bring as much as you want, doesn't necessarily mean that you should. Just lugging my gear around from place to place (even though I love my ThinkTank Airport International 2.0 which made it easier) and trying to keep it secure just added another thing to take my attention away from focusing on enjoying my vacation. One reason I did bring a backup body was in case my 5D3 were to crap out. So, if you think a backup is very important, then you should bring both. If not, just bring one.
For those that say you should take just the 650D only... if I am going on a vacation to a place where it is likely the one time in my life to visit and capture some pictures of, I'd want to take the camera that is going to give me the best possible results, that I have. In this instance, it would be the 6D.
The 17-40 is a great lens. I know you love your 10-22 as I did also before I sold it when I moved to FF. But, I am pretty certain that you will be extremely happy with the results of a 6D + 17-40 when compared to your 650D + 10-22.
Sirrith wrote in post #16124788
Just do the HDR in post, not in-camera. Much better results.
I agree with Sirrith. Do the HDR in post. If you were referring to being able to bracket more than 3 shots, then yes, the 6D wins here and is a good reason for choosing it over the 650D.