What is your take on high efficient speakers vs. low efficient speakers?

My speakers are home-brew, look like Klipsch Lascala on steroids, average sensitivity is 105dB and I tri-amp with an analogue active crossover (subs, bass/low mids, mids/treble)

For me the micro and macro dynamics associated with high sensitivity (100dB+) is something I could never do without, and being able to use very low power amps is a definite advantage

BUT

-big horn systems image differently, you either love it or hate it

-ANY noise or distortion will be MAGNIFIED and unbearable - this is real - any RFI / EMI, any noise on the AC lines, anything from the outside world (or from your electronics) that would mostly stay hidden on a low sensitivity system will be exposed and you will have to deal with it or live with it!

-caution with gain structure is important, otherwise say hello to noise (see above remark) and hello to all the issues some preamps can have when used with the volume potentiometer at the lowest settings (bad stereo tracking, loss of dynamics and definition, etc) YMMV depending on the quality of your preamp(section), but shouldn’t be overlooked

Great that there are lots of comments and examples here for your question...  I have to agree with many here regarding higher efficiency speakers over inefficient ones.  I've had both types, and in each case, micro-detail has always been notably better with higher sensitivity speakers.  I had 89db speakers and using the same electronics, my friend brought his 98db speakers in and with my exact same electronics, you could immediately hear the micro-detail difference just queueing the stylus !  I was astonished as the music seemed more real and alive.  I sold my beloved speakers soon after and bought 94db ones and experienced that same more alive, real and micro-dynamic improvements.  Then moving to much lower powered amplifiers (ie...  less components that "touch" the signal) even more micro-detail was apparent.  So now, I am ordering my last set of speakers at 101db efficiency to take advantage of my low-powered amplifiers.  I don't listen at very high volumes but it's the details, soundstage, and realistic portrayal that really capture me.  There's only one exception to the inefficient speakers I've found to those that are efficient that I've experienced and that's the Magnapans.  I heard music played on the 3.7i's and the upper mid-range/treble was some of the most accurate and micro-detailed I've ever heard.  This is proof that there are exceptions to every rule, and in the case of the Maggies, the extremely light weight diaphragm is the reason for the terrific micro-detail, despite their inefficiencies.  Everyone's tastes in music and how it's portrayed is different, and that includes speakers and corresponding electronics, so if you enjoy how your music is reproduced with your stuff, that is what's most important.  .  

I also prefer high efficiency speakers but they have big/many woofers to produce bass (Legacy Focus and Signature IIIs).  Noise is more prominent than lower efficiency speakers but so what, dynamics are easy to get, especially when loud.  I play my jazz and classical music up to 95 db all the time in a custom built listening room (expensive).   Average volume in the 80s db.   

Harbeth 40 series (top) speakers are rated inefficient with high impedance.  Relatively easy to drive with moderate power.  They never failed to sound excellent, especially nice in the mids.   At shows, no one says best in show but always musical as the mid-range is 90% of the music.   Much like Von Schweikert speakers.  I would rather own Tannoy's than most horns or stats (had stats for 20 years in my youth).   My wite of 24 years hated the big stats (ML Monolith IIIs) as they had limited dynamics, beamy, limited bass in particular.  I've moved on then to dynamic speakers and not return to stats ever (including good sounding Soundlabs).