The 5D3 should be cheaper than the D600? That's a bit ridiculous don't you think?
Nope. In terms of sensor IQ that is where it sits. It is simply not a competitor to the D800. At the same price or slightly less then the D700 it is spec'd well and would be a very solid competitor.
And who exactly are they behind? Nikon isn't even making the sensors Sony is, so.... who exactly is Canon behind again?
Canon is behind Sony. Since Nikon uses Sony sensors, Canon is also behind Nikon.
Why doesn't everybody say I'm gonna go buy the Sony XXXX then?
Because Nikon has the better lens collection vs. Sony. And because Sony keeps playing with technologies that aren't ready for prime time yet. For example, I would never consider Sony's FF body because of the EVF.
I think the D800 and similar cameras are good for us as Canon owners as it forces Canon to give us better and/or cheaper products, that's the beauty of a free market with competition, but outside of the sensor what is the 800D really better at than the 5D III?
It doesn't need to be better at anything else. It's spec'd about the same on everything else, and the sensor is a significant step above Canon's.
Put simply the competition is differentiating their high end bodies on resolution and shooting speed, which makes sense. The 1Dx is fine for its market segment, but Canon is trying to differentiate the 5D3 based on nothing more than AF. The D800 has comparable AF and a better sensor. The D600 has slightly worse AF and a better sensor. What makes Canon think the 5D3 should be positioned against the D800?
If Canon did what I said above, then the 5D3 would be priced against the D600 and there would be a high resolution body priced against the D800. Canon can't deliver the noise and DR that Sony can right now. But they could scale their APS-C sensor to 45 MP FF. It would have more noise and less DR then the D800, but also more fine detail, and if it was otherwise spec'd and priced to match it would be a wash. Lots of people jumping ship for the D800 would stick around for such a Canon body.
But that body doesn't exist, and Canon expects us to pay the same price just to get decent AF. Ridiculous.