I normally agree with your posts, but not this one. A transducer engineer like Doug Button (he worked at EV when I did, and then again at JBL when I was there) or Rich at ATC would agree with my post (maybe not exactly the way I say it). The physics of the speaker is a balancing act: if you want more efficiency you give up other advantages. Im not saying this is wrong, it’s simply a choice. A moderate efficiency speaker (86dB 1w/1m) is not a mistake either as it is just a different choice that enables other performance features that high efficiency cannot offer. You cannot have it all. My point is simply that this thread seems to universally promote that high efficiency is the primary hallmark of high performance and that is simply not true. It can be important if you need High SPL, or like horns or big wave-guides (which can image well), or use speakers in a highly reverberant environment where narrow dispersion is an advantage, but these conditions certainly don’t exist in every room or for every listener. It’s a trade off and is not a "good or bad" or "right and wrong" thing. Decide what you want, then figure out what speakers do that.
A good example of deciding what’s important to you is a listener in a small space; a small stand mount speaker with excellent low frequency output, say a LS3/5a type KEF design would be a good choice. Super high efficiency is not gonna happen in this type of design. If a listener wants wide dispersion speaker because he/she wants it to sound the same anywhere in front of the speaker, super high efficiency is not gonna happen. If a listener wants super low distortion because they are in mastering or recording, then super high efficiency is typically not a goal. The hardest part may be understanding what you want in your space vs what other people want in their space, as the reviews say this is good or bad but don’t really discuss the space or the listeners goals much. Whether it’s good or bad is ALL about matching your space and your goals with a speaker. High end speakers are not good or bad on some universal scale. There are too many engineering goals/design features to account for that define good or bad in a given space. Efficiency is just one of these many features.
Brad