Deformed hard pellets are not necessarily equivalent to soft pellets in flight characteristics. A good example is the 3" RP .410. Shot hardness (#7.5) is really excellent, but shot scrubbing causes early attrition of at least 25% of the payload. I suspect an 11/16 oz soft shot 12 ga load would throw a very different pattern.

Again, I would bet on pattern density insofar as lethality is concerned.

Sam