New, Inexpensive Speaker for SET amps

This speaker looks VERY interesting and it is affordable:
I am also interested in the benefits offered by efficient speakers and SET amps. I saw on the Moth \web site that the speakers are rated at 94dB efficiency. I understand the meaning of speaker efficiency, but I have never seen a discussion on the amount of amplifier power required to drive a given efficiency to a reasonable level. Perhaps someone could offer some info on this.
Each 3db increase in efficiency reduces the amplifier power required for a given listening level by 50%. So, speakers with 94db vs. 88db would require an amp of only 25% as much power. Just how much power that is,of course, depends on your preferences.
Has anybody heard the Acoustic Research AR1 speaker in a SET system? 95db and current Stereophile Class B and can be bought on the web for $1300-$1400 a pair ($2500 list)Also, a built in poweered Sunfire sub. It seems good on paper,but I can find no posts on real world users or dealers who carry them here.