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

@larryi That's what I wonted to hear from you.  You're on the right track. 

Here is my take on high efficient speakers. They sound great when done right. Unfortunately, it’s not that easy to design an efficient speaker. That’s why speaker companies rather make inefficient speaker by complicating the design. Simple is better but it takes longer time to implement - that’s how I see it.

As someone above mentioned, most of these high-efficiency systems do not do really deep bass.  That is one of the tradeoffs that attend going this route.  For my taste, the very best woofers for a high efficiency system must be very agile to match the other drivers.  This typically means very light paper cones, and somewhat limited excursion (I particularly like drivers with pleated fabric or paper surrounds).  I've heard systems with twin 18" woofers per side that were still a touch limited in very deep extension, but, I really did not care much--the bass was clean, fast, and had "tone," which is more important to me.  I have no interest in a subwoofer, and several of my friends who are horn-based system experts say that subwoofers are NOT the way to go. My system has very modest twin 12" woofers per channel (pleated fabric surround, alnico magnet) in a Jensen-Onken bass reflex cabinet; it does not do deep bass.  With every system, you have to live with some limitations.

Big fan of high sensitivity speakers especially because they work well with low power SET amps.

I prefer high efficiency but I don't undersize my systems so I get bass into the 20-30hz range on most systems. I find higher eff designs to have a more realistic sound quality if done right. But many are too compromised in size. But sadly so are most of the loudspeakers offered today. Shipping costs and material costs all lead to smaller and smaller designs. I get 1 tear in my eye at audio shops it's all too small.