Speed is a non-issue at this point because I believe Kakashi has improved enough to be ranked in the same category as Itachi. Itachi with a full tier advantage against Kakashi (w/sharingan) [Part 1] was able to respond to him, despite being slower. Well, it comes down to feats and without MS, that true-heir stuff doesn't really mean anything. And Kakashi has more lethal ninjutsu than he does, thus I see Kakashi having the advantage (especially considering his clone feints). The author hasn't touched base on it yet and his usage of his ninjutsu so recklessly leads me to believe he's probably managed to make his stamina grow and at the same time asserted more of a control. I'd say a little of both, but I don't think he has a flat 3.0 in stamina anymore. He's definitely pushing a 3.5 or 4. Not only that but he surprised Tobi who stated "Wow, that was fast" when Yamato ambushed him with the wood. That's a perfect example of what would happen to Itachi, once a clone was able to attract Itachi's full attention.