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

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. 

It's just wrong to think that hi eff doesn't do low bass I have bass horns that can bend doors and make your eyes resonate some I designed are used in military simulators to replicate explosions and gun fire. Just because in your limited experience you haven't heard deep bass in hi eff doesn't mean it's not available. It just means you made major compromises in size.

I use most all types of amplifiers inc SET with a 6-watt SET I have horns outputting a solid 30hz and getting room lock. Those dissing SET never used them or they SET their system up to fail.

Low-eff designs can suffer from dynamic and power compression. It's not possible for those designs to replicate the natural dynamic range that real music has and if you play those designs at a higher SPL level many have power compression.  If you can deal with reduced dynamic range and need a small speaker maybe low-eff is for you. If you enjoy the dynamics that real music has and want freedom from power compression at higher SPL levels and can deal with a larger loudspeaker then hi- eff most likely is best for you.