I love my Canon gear for my wedding photography. I love the 600EXRT's built in radio, I love the 5D3's not too big filesizes.. lenses etc... functionally everything is great.
But... but... that dynamic range My style of shooting lends itself very well to have that wide range as I prefer to underexpose for the highlights and bring back the shadows, but I'm very limited with that 5D3 sensor.
I get the itch to switch over to Nikon for the DR alone but then I'd be giving up on a lot of functional things that I love about the Canon system. How likely are we to get Nikon-like DR in the 5D4? Is this even something Canon cares about for it's consumers? DR actually went down from the 5D2 to the 5D3 so that's not a promising sign.