heh, yeah, you left yourself wide open detail!
the individual out mixer controls the levels going out the mix out, so you can have a different mix on the headphones than you do on the main outs.
You coul also use it as a cue function, where you have pads brought down in the main mix screen, but up in the indi mix screen so you can test out pads live before sending it to the house speakers.
The mix out is a little lower than a regular headphone out, but it's louder than the mains, and why mess up a beautiful machine with a headphone out. Even well done, you really dont need it, you aint gonna carry the 60 around, and you can use the headphone output of your mixer, which you will want to get eventually.