I 100% agree, have one of these no-names cables. Quality is very bad and cable is prone to interference making pinkish artifacts on screen. I've been thinking of reusing its connector with 360 cable as you mentioned.
Interesting, but if I'm not mistaken those HDMI converters would be exact quality as component with some additional input lag. Pre 1.6 Xboxes can also output RGB via VGA with modded bios, I don't know how it compares vs YPbPr in terms of visuals.