For the next HW iteration: It would be great if black wires was reserved for ground only, and not used as a color of an actual channel. Yes, there is white shrink tubing on the actual channels, but it is still easy to mix them up.
Yes indeed, this was probably the most confusing/annoying thing when I first got my Logic Pro 8, and still bugs me every so often now.
Changing the wire colors to start at brown and run through to gray for channels 1 - 8 rather than 0 - 7 for the black through purple coding presently used makes good sense and allows black (or green with a yellow stripe?) to be used for common/ground.