I own both the 6D and 6D2 and it's really hard to go back to the 6D once you start using the 6D2. It operates a lot faster. The UI is faster. Taking photos is faster. AF is faster. You can tap to focus as well as tap to shoot (though the tap to shoot was way too slow to be useful; it's so much slower than a smartphone tap to shoot). It makes it fun to shoot. It has a touchscreen. The screen is flip out and articulating so you can get really creative in your framing (no more lying in the dirt for that low-high shot). The 6D was almost worthless for video because the AF was awful (remember, 6D2 had dual pixel AF while the 6D had contrast).How is that possible when is has no more DR than the original 6D?!? DPR and some other review sites made it abundantly clear how terrible that was, and yet people are still buying it. SMH.
And the resolution difference was noticeable.