So what's it going to be like when 4K is thrown into the equation? Worse, probably, but it might not be too bad. The point is that the technology around multi format, multi resolution recording is maturing and not only is it going to be much more stable this time around, it's going to be easier too. You just need some familiarity with the basic terms and concepts.
Here's a quick video made by Abel Cine, showing how to connect the new AJA KiProQuad to a canon C500, so that you can record the output in 4K 4:4:4 ProRes. And no, it doesn't look too difficult!