The thing that amazes me is that the transposition expertise of the pros who play in symphony orchestras. I have never understood why they just don't print out the notation, for their own instruments, since we've had that technology for a long time now.
Then those same folks also play the old style horns without any valves. Although I like to watch them, I have no interest in learning how to do that. I know a pro fr. horn player who plays a horn without valves and her articulation is incredible. Of course she also has a triple, made in Germany, for around $17,000.
And then there's improv.......
Stan