FWIW I'm really bored with 24-70 zooms, so I ditched mine (24-70 f/2.8 L) and got a Ʃ35 f/1.4A instead to bridge a gap in my range of wide to standard prime lenses. I find that I am shooting with primes more and more often, with really satisfactory results. Often I will have a wide or standard prime on the 5DMkII and a tele-zoom on the 5DMkIII. My 24-105L and 17-40L get most of their use when I travel, the 17-40L is almost exclusively for holiday use .
Yes. I have the Sig 35 Art and it just forces me to make better composition, and its colors and sharpness are just insane. I almost can't take a bad image with that lens.
I plan to pick up a 7d2 (if it isn't just a Bigfoot riding a unicorn) and then keep he 35 on the 6d and the 70-200 on the crop.