Well, this part is wrong to start with.
If you take two boards, one is stiff SL board with 7m radius, and another is infinitely soft board with double the radius. Which one will go round tighter arc? Second one of course. infinitely soft board will be fairly boring to ride, but hope you got the idea.
I haven't read topic regarding sidecut, but will do that tomorrow at work.
ps. That MK sounds interesting, might be what you're looking for.