Back of the napkin math is back of the napkin math. If I wanted to deep dive into statistics, I would be one of those psychotic people who does HERO System chargen math in their heads.
Anyways, the point is that, until you get to the truly insane levels, both the Katana and Red Samurai Katana are rarely going to have you losing hits. And when you have enough dice to make your accuracy a real limiting factor, called shots are a good way of mitigating that and making things nastier all the way around. And a highly skilled individual is probably more likely to go making skill shots anyway.
