The Misono comes overly convexed out of the box, from buffering, indeed. Get rid of that factory edge and you will be fine.
The Masahiro factory is highly unpredictable. I got a new 240 with an extremely one-sided edge, and a 180 with a more 20 degrees right and 8 left, but still highly off-centered to the left. It doesn't matter. I put a 13/17 degree on it and see if it works.