My argument is that this efficiency as it relates to speaker performance is a complex issue, much more than a simple number. You forget I am engaged with dealers and end users who ask these questions (and similar ones) quite often. The desire to reduce a complex issue down to a simple one is very attractive when the subject is complex. THAT is my point, not that there aren’t times when facts are facts.
Since you own DH1A, I can use a historical reference: I bet you remember many people arguing the advantage of 1.3 inch throat driver/horns (EV) vs 2 inch driver/horns (JBL) and vice versa. That discussion was often reduced to focus on one attribute (throat diameter) when really it was a far more complex issue than that, depending on what you were trying to accomplish.
Brad