So in your honest and technical expertise which I do respect, a speakers sensitivity rating or level is a significant factor in choosing a speaker.
I will not say it is not a significant factor; however, I will say that having a pair of AA's which I have setup with a listening position 9-10 feet away and listened at levels as loud as I would want (85dB peaks - slow response, C scale on my RatShack meter) I had no issues at all.
Since you are 6 feet away and have a max of 80dB, it seems like you would be perfectly fine.
Now when your brother-in-law comes over, gets drunk and decides to "crank it up", he may find the limits.
Most AVR's have a place where you can limit the maximum volume. I always set mine at what I consider "the maximum sane limit" I would want to listen at.
Efficiency becomes important if you are sitting far away from the speakers and like to crank it loud. Generally we have louder peaks in HT content, so it is more relevant for HT. It is also important if you want to use your dad's (or grand-dad's) 10WPC tube amp from the 60's!
Having been around for a while, I have never read anything about the AA's being weak, or otherwise not able to play loud enough.
BTW, how do you feel about the bass of the Polk A3's?
...and what receiver?