Mitsu is very logical. However, as much as he is logical he is also imaginative. His intelligence is above average, which is to say that he is probably top tier in his class, probably as Shinichi was. Shinichi at his age was very similar, if not more clever, but less imaginative. I think there is a balance between the two, young shinichi and mitsu, where they share similar intelligence, but Shinichi was taught to be clever and think on his feet, and Mitsu was brought up to be imaginative. This is probably why Mitsu can think up great scenarios, but until he gets pushed in the right direction his deductions will likely be wrong. We saw this in the Desperate Revival arc. When not thinking of Conan he had some interesting ideas, and when he heard the partial solution he got it almost immediately. I think Mitsu, with the proper guidance from Shinichi (aka Conan) he can be the next great HS detective.