Putting aside all the battling about which one is better than the other in which way...
At the end of the day, I think the biggest takeaway from the whole experience for me was the self-assessment aspect. I think that many of us suffer from a compulsion centered on acquiring more and/or better gear which is what has led me to owning as much as I do. Going through the thought process and truly evaluating what my needs are was really eye-opening and valuable. I think it will be easier for me to let go of some of the gear that I kept around merely because I thought there "may be" a chance I'll need it. Coming to grips with need vs. want or potential need will ultimately help me to triage what will remain in the collection. Consolidating and downsizing not only lets me get rid of the unnecessary stuff, but will allow me to save up money for a single high dollar item that I'll use all the time i.e. the new ff body/bodies to come.
That's a great point, John. Ego is undoubtedly a part of our profession/hobby. I have learned the hard way that I don't have to have everything, and I have reached a point where I don't add anything to my kit without subtracting something. I'm in the process of selling one of my cheapest pieces (85mm f/1. and am replacing it in my bag with the new 35mm f/2 IS. I have a great zoom covering the focal length (70-300L), and I also have the 100L and the 135L. I decided that I don't really need the 85mm, and a friend is very happily buying it off me.
P.S. I've also learned that there are some very good lenses out there that don't have a red ring on them. I've actually replaced two red rings with other branded lenses.
Good points, true.
However, it isn't necessarily all about ego. I spent over ten grand on a lens this year, a $12,800 lens to be exact. While I believe there may be a very few people who have egos so large that they might actually drop that kind of money on a lens "just to have it so they can brag it"...I think such individuals are VERY, VERY few and far between.
I bought the EF 600mm f/4 L IS II lens because I needed it. I'd been shooting with the 100-400mm f/4.5-5.6L lens for a while. The 100-400 is an excellent lens, it produces wonderful shots that can be very sharp. Don't get me wrong, I love my 100-400. That said, it wasn't letting me realize the kind of results I really wanted. A 71mm entrance pupil at 400mm just wasn't large enough to produce the kind of soft, creamy boke that I felt was necessary for my work. Not only that, the lens only performed ideally when stopped down to f/7.1...anything wider and the image softened, visibly (even with AFMA and a trip to Canon for calibration.)
The 600/4 L lens has a 150mm entrance pupil, which does WONDERS for background boke. The lens is razor sharp wide open, so I can get more light and use lower ISO settings. Combined with a TC, it gets me 840mm of significantly greater reach (subject size in the frame is relative to the ratio of focal lengths squared...(840/400)^2...my subjects increased in the frame by a factor of 4.4x!) Overall, between brighter and larger subjects with blurrier backgrounds, I have more detailed photos with more isolated birds and wildlife. I'm able to start realizing the kind of results in my work that I have worked for for years.
I currently own a 7D. The 7D is a great camera. I got it for an incredible deal ($1200 in 2011!) It has a fast frame rate, and does reasonably well at high ISO. However, similar to my 100-400mm lens, it has become the primary limiting factor. It does not do all that well, relatively speaking, at any ISO above 1600. Even ISO 1600 is lacking by todays standards, and can be too noisy in sunrise or sunset light (even with an f/4 lens). The AF system, while certainly better than the 9pt systems I started out with, has it's issues (namely, the constant inter-frame jitter that results in some frames being tack sharp and others being just the smallest degree too much out of focus that they can't be keepers.)
My only two options, given the expenditure of thousands of dollars on the 600mm lens, are the 1D X and 5D III. The 1D X would certainly be my ideal choice...but the 5D III is absolutely no slouch. It's AF system is blazing fast and extremely consistent compared to the 7D, and it supports f/8 AF, meaning I don't necessarily have to give up my reach (1200mm f/8 vs. an effective 1344 f/5.6...given equivalence, the f/8 on a FF sensor is actually just as good, from a total light gathering standpoint, as f/5.6 on APS-C). If I had the money, I'd buy the 1D X. It has absolutely amazing quality at unheard of ISO settings, and at every ISO setting from 400 up, it performs visibly better than any other camera I know of, including the 6D. Since I cannot afford the 1D X, the 5D III is my choice.
My desire to own the 5D III and 600mm f/4 L II lens has nothing to do with ego. It has everything to do with achieving my goals in my work. I am fairly humble about my work as well...personally, I am never quite satisfied with it...there is ALWAYS something I can do better, something I can improve. I hope someday I'll have developed the skill to achieve exactly what I want when I point my lens and press the shutter button, but I know quite thouroughly that day hasn't arrived yet, and won't arrive for some time still.
@John, I applaud your decision to step down to the 6D. For your needs and goals, it sounded like the ideal decision. It got rid of a camera you were rarely using, replaced it with a camera you use more, allowed you to continue to gain value from your collection of EF lenses, and gave you some extra funds to put towards a future camera that you will use even more. I can't think of a better reason to make the decision you did.
That said, @TWI, not everyone who uses or wants something better than the 6D is only out for an ego trip. There are legitimate reasons to NEED the 5D III, to even NEED something much better than the 5D III. Sometimes debating the minutia of technical details helps people figure out what they truly need, and make the appropriate decisions to buy the gear that best fits their goals. I need the 1D X for my birds and wildlife photography, and I'll "settle" for the 5D III. For my astrophotography, the 6D's lower high ISO noise levels actually make it the better camera, and a lens like the new Samyang 10mm f/2.8 manual focus lens would be ideal.
Different needs demand different things. It's ok if all you need is a 6D. I think where the debate enters in is when you get people saying the 6D is a superior camera to the 5D III, simply because it has a "better" sensor. While it may have some superior attributes, it is by no means a superior camera.