What happens when your camera DOES stop functioning, and results are impossible?
backup bodies cover that
I wouldn't haul a D800 out for anything action related.
yes, it's a little slow on fps but so's a 5d2. most of my subject matter only moves when the wind blows.
I kept a 7d for speed until I dumped it last year. Waiting to see what a 7d2 will be like, or even the 70d. 40d, 60d, and some old rebels still back some Canon glass for now but rarely get used.
For everything else, d800/5100 and k52s work just fine and I no longer have to deal with dreaded pattern noise.
I DO miss the 7d when trying for BIF shots, especially in low light.
But that's the thing, I select my gear for specific kinds of shooting.
If I wanted an all-round, general-purpose body I'd have to make compromises...
I don't like compromises.
File sizes are not an issue either. I capture a small jpg with each raw, use those for a quick catalog to review shots to select for post.
Most post software will also allow you to batch-process so if you have at least a reasonably capable computer, you can continue to edit while running a batch.
So, other than limited fps, but not significantly different from previous canon FF, I've not heard of any significant impediments to using a d800 in the real world.