Caveat, I’m just a dumb paramedic with two decades of experience treating GSWs and other assorted trauma and the benefit of a cadaver lab, but…
The point is moot. No matter which scoring ring you use, the effects will be largely the same. Connect the two circles into an oval, and you have an excellent and anatomically relevant area (perhaps too wide, but I digress). I am a fan of using an imaginary line drawn between the armpits as a vertical reference on the human torso. My only other observation is that assuming a tendency for shots to go low due to common deficiencies in technique, I think a habitually higher aiming point is probably a good thing.
As you say, differences in philosophy.
At any rate, seems like an excellent drill that I look forward to incorporating into my practice!