Before buying I made probably the same thoughts, like most other ambitious amateur photographers as well. I started many years ago with a Canon 1000D, and managed with years later at a 550D, which I used also for years. But at some point you get now times to the point at which one limits the old camera. In particular, the noise behavior was enough some point no longer my growing demands, the camera could have been bigger and I missed just some sensible (!) Settings, such as an auto-focus correction, which were my top two criteria together with the noise performance. First I looked at the 60D to Better adjustment options offered them, but the picture quality was basically the same as that of my 550D. This was followed by an assessment of the 7D: faster and bigger is better and settings it also has the autofocus system is really super. But she has an identical, or very similar sensor. So take 1200 euros in the hand, for an advantage that I do not necessarily need personally? No, not this time. A further look at the first preliminary tests the 70D gave rise to the question whether I should take such amounts into their own hands again, to re-buy a crop camera and sometime but then switch to full-frame. To select now were for me the 5D Mark III, the 5D Mark II and the 6D. I am busy for weeks with comparisons, private Try the merchants, reviews and tests in magazines and the Internet. So for around 2250 euros I bought the 6D along with a Canon 24-105 L. alone the body of the 5D Mark III would have been 600 euros more expensive than the 6D with the lens - with said lens even 1000 Euros. But why I have this amount not upped the ante, for example, to benefit from the clearly better autofocus? Because I personally do not need this! Apart from the fact that thousands have come from professional photographers for many years with a 5D Mark II the most marvelous that even has even fewer focal areas. A higher burst speed I also do not need, because sport does not fall in my repertoire and I'm not interested thereto. In my photographer-existence, it might have been two situations at weddings, where 1-2 frames per second might have been better. And this provides the 6D towards the 550D!
But then why not 5D Mark II? The differences in noise performance are marginal and some tests have confirmed the following order in the quality of the image noise, starting with the best values: 5D Mark II, 6D, 5D Mark III (However, in the last two, the technical reports argue repeatedly). But even here the differences are so minimal that you can leave them safely ignored. A difference I could not really see a direct comparison. Was much more interesting because for me the average cross-type sensor, which enables focusing even in low light and should be even better than the sensors of the 5D Mark III. I am often in situations where it would simply take too long to adjust the focus point. For anything but the simple focal areas work perfectly and quickly, if this is not a comparison with the cross-type battery of the Mark III. Do you need this, you need read no further and here, the 6D good conscience turn their backs.
I would also like to emphasize that the so often mentioned, technical features such as GPS (-Tracking), WLAN, etc. have not influenced my decision. How often are 99% just nice to have. In practice, I never use the WLAN feature actually. Even the Live View function, I use only the exact pixel, manual focusing. For nature photographers operate on the smartphone / tablet might be interesting or as a prime self-timer with the ability to assess the scene in front of the camera. The GPS function makes for me only on photo tours or trips sense. Although these features work very well, really need it, I have it so far however not. For use with the tablet I would like to mention that this is so far limited in the case of Apple device that you so far yet to install the iPhone app for this purpose. This is geared to the smaller screen of the iPhone, on an iPad you have to resize it, which I personally do not like so much greater.
Have fun, however, makes the possibility of including in a bracketing up to 7 shots. The autofocus correction is great if you times caught a lens, which is 100% non-centered, but only to 99%. However, the built-in HDR functions I use also, since I like to put together my own HDRs. The multiple exposure function is nice, but not necessary for my purposes. First class, however, is the Silent function Allows the camera instantly takes much quieter. I was asked about weddings of church personnel, that thanked that I was the one who did not bother the ceremony. Not only because of the quieter trip, but also because I was able to do without a flash.
For picture quality (compared to a crop camera) I just want to say at this point that here make worlds collide. Great noise performance, excellent sharpness, amazing detail reproduction, it is simply fun to work with this. I crunched in the 550D as early as ISO 1600 with his teeth, I look today at ISO 3200 every time again on flawless photos. Even at ISO 6400 is still everything in the green area. For smaller prints (10x15) you can go even up to ISO 12800. It's also great that it is now possible to manually select the ISO and intermediate steps that you can set the custom functions on the dial (C1, C2) free.
As already mentioned, I ordered the 6D along with the kit lens 24-105 L 4.0. The name Kit lens has not deserved in my opinion, since this is a really good deal. Well, it does not have a 2.8er panel, but this is in my eyes the only weak point. Distinguished himself at full aperture, the 24-105 4.0 L still very sharp, the operation is really well done and it is sturdy like a tank. The image stabilizer works very well and reaches approximately 1/25 sec until its limits Mind at 105mm! The problem arises only in low light in combination with movements knows that the 4-panel naturally not compensate, so I like to take a flash to here. An alternative with greater luminous intensity would the other hand, the 24-70 f / 2.8 L II USM. Here, however, we are moving at around 2000 euros and have not yet purchased a camera I would 24-105 4.0 L also a 24-70 L prefer because the focal length is larger, but the image quality is not worse than that.
My personal conclusion is to the effect that this camera is a very good and effective alternative when you want to photograph any sport. Personally, I have the additional cross-type never previously missed because the existing for my purposes so far always fast and precise enough were also at weddings. Need contrast, a highly complex autofocus with only cross-type sensors, the choice should fall on the 5D Mark III. Here prefer to save something, than to buy now and to compromise. In addition, I recommend the kit from 6D and 24-105 4.0 L lens to take more for the money you will not get. Of course, only if permitted by the budget and / or you do not have better lens. But even worth the purchase of the lens if you do not shy away from a sale.