It was a year ago when I was looking at the 6D. My best camera at the time was my 60D. I used it for fashion. With the 60D, all AF points are cross type. I would switch the AF point, depending on how I was shooting the model. The 6D has only one cross type AF point, the center point (and also has a vertical line AF point in the center). Everything else is vertical or horizontal. It would have been a step back for me. My choice was stay with the 60D or go to the 5DM3. I have never regretted getting the 5DM3.
On the money, insure it. It's not that expensive. Then forget about what you're carrying.
Finally, on using few settings and options, this autumn I was one of the official photographers for the high school marching band. There were a few of us, mostly photographing them at night time football games, along with a half dozen competitions. There was one guy who has a Nikon D800 with a 70-200mm f/2.8. He's a super guy, very nice, very successful in business. For one of the competitions, he and his wife spent 12+ hours supporting the day. That's just one of many stories I could tell. This is a solid guy. They're nice people.
The D800 is a fine camera. You can debate which is better, the D800 or the 5DM3. For night time sports, which is really what marching band is all about, the 5DM3 outperforms the D800, sooc. No matter, it's a very capable camera and could easily get super shots. This guy shoots auto. He'll put the ISO as high as 800. He's pleased with his work. In contrast, I shoot manual, f/5.6, 1/500s, and ISO 12,800 (for the field performance). I have a long way to go with my work.
Are you happy with your pictures? If you are, why change? You've got a fine camera. Perchance it will encourage you to go farther with your photography!
In closing, sometimes in photography, you only get one chance. The camera won't make you a better photographer. It will however enable you to do things you can't do with a lesser machine.
Exhibition Performance of West Virginia University at Oakton, VA, Oct. 12, 2013.