It's kind of hard to argue against sage mode for someone who's not one of the ridiculously powerful, but I will point out for Kakashi's sake that he specified that he was surpassed in the sense of Naruto being able to create the Rasen Shuriken. That's all he meant. His ability to make a move that Kakashi or Minato weren't able to. Also for Kakashi's sake, no one but Kakashi is fully aware of what he can do. If we take his knowledge of 1,000s of jutsu literally then it would appear he keeps the majority of his cards close to his chest. Yeah, he tends to rely on a small handful of moves, but that kind of makes sense doesn't it? Anyway, I reiterate Sage Mode is crazy, and unless Kakashi has the perfect move to counter it, up his sleeve, he probably won't be able to keep up.