I've been on POTN for about 3 years now, basically ever since I purchased my 60D. I would like to say that I agree with much of what is being said here:
- I've seen many great shots posted that are from the crop body cameras, I've also seen many average to poor shots from FF cameras. Much of what I see is truly the photographer, some the cameras, and some the glass.
- Just because you have a FF camera, there is no guarantee you will be a better photographer. Either way, you need to make the shot, not just take the shot. I've been on group shoots where the person that had the best shot was using an Rebel XSi.
- Those with higher end FF cameras, like the 5DIII or 1DX, spend a lot more time, and give fourth more effort to go out and get a great picture. They go on photo expeditions, climb mountains, or are out looking for that perfect sunset. They also may have studio lighting, flash triggers, filters and high end L glass. They are often in the business of photography; portraits, magazine shoots, weddings, etc. It can more than a hobby, so for them a FF body and everything else that goes with it is justified.
- Those of us who just enjoy photography for the fun of it, and not something we depend on to make a living, like a camera that can do a lot of things including sports, wildlife, and movies. We don't want to spend as much time, money, and effort. We will be very pleased with a crop body and one of the best being a 70D.
I went through the same dilemma as the OP, I wanted to upgrade my 60D. I looked at micro 4/3rds (M5, M1),I looked at the 6D, and the 70D. I decided on the 70D for a few reasons:
- The cost for the new body was small, the difference between what I sold my 60D for and the 70D was only $400.
- That marginal cost bought me a better AF system, touch screen controls, Micro focus adjust, slightly better IQ, built-in wifi, and a slightly better viewfinder. Some even claim slightly better high ISO performance.
- I didn't want to sell my EF-S lenses and buy new EF lenses. Not to mention, I'd be purchasing the lower end L glass, which in some cases would not be better than the glass I already have.
I came close to going FF since the 6D was much cheaper than any FF camera that came before it. However, the 6D was lacking some of the features I wanted like a better AF system, built in flash (that can also trigger off and camera flash), and hated to lose the articulating screen. In the end, I decided to wait, get the 70D now, and maybe go FF down the road when the 6D Mark II comes out in a few years, or maybe go mirrorless when that technology is more mature.