Upload & Sell: Off
Erm...it's not just about the MPs/IQ, if it was they would share the same sensor to meet your needs. A 1D, in this case the new 1DX is about speed, Better/faster AF (with it's own dedicated CPU) and FPS; twice as fast. You can't put two 5D3s together and get 12 FPS.
Comparing their pro top dog to the prosumer top dog...sorry is just...useless. They're both killer cameras, what Canon has to offer. Canon doesn't compare the two. Only we do. They're made for differing target markets.
I wouldn't say comparing the 1DX to the 5D3 is useless and I disagree that Canon doesn't internally compare products as Canon has a pretty long track record of removing functionality or features from their products to create so called "market segments" for their products. If Canon did not compare their products internally then the 5D2 would have had a better AF system, all EOS bodies would be able to spot meter by the selected AF point, all EOS bodies that shoot video would allow for uncompressed video out via HDMI, and the list could go on. It seems Canon is doing less of this with the 5D3 and 1DX and hopefully it continues going forward.