I guess I'm spoilt because I fly mainly very well designed profiles -- most of which have virtually no coupling in knife-edge, which means that they're really quite easy to fly on the sticks.

I have to admit that flying a plane that kife-edges very poorly can be a handful -- but I only ever had one plane (a fatty) that flew like that and I got rid of it.

We've got a guy in our club who can fly almost anything knife-edge -- he delights onlookers by doing an entire (dead straight) KE pass along the runway with his CMP P51 Mustang. No mixing either :-)