just to clear something up. when kakashi fought itachi, he got owned. but this was only because the genjutsu itachi used would own anyone except someone with sharingan, or someone who can fight without looking at the other person's eyes.

Also kakashi can't copy kaiten because you have to have unbelieveable control of chakra points. kakashi also can't just all of a sudden copy the 8 sealed gates. it takes training. if you don't believe this look at the first fight between sasuke and lee.

sasuke could see everything but he couldn't copy because he wasn't trained to fight that fast. later on its mentioned that he could go at lee's speed but only for a short period of time, because he doesn't do anywhere as close as much training lee does.

So then u can overlap that to Kakashi may be able to go at Gai's speed, but not for long periods of time. And enless Kakashi already has unbelievable chakra point control(which i doubt, because hyuuga's leader was surprised neji had that much control) he couldn't copy the kaiten, because that takes training in chakra points.

but kakashi was ordering the other 2 jounins in kakashi vs itachi, so he is still probably way up there