My take on this is, that if you are not stuck with worrying about keeping efficiency then you can use components and crossovers that may provide a flatter frequency response without compromise. Often you have to compromise the response to keep the high efficiency. Having said that I think there are good loudspeakers in both camps.
What is your take on high efficient speakers vs. low efficient speakers?
Consider both designs are done right and your other equipment is well matched with the speakers. Do you have any preference when it comes to sound quality? Is it matter of economic decision when it comes to price? - power amps can become very expensive when power goes up, on the other hand large, efficient speakers are expensive as well. Is your decision based on room size? I'd love to hear from you on the subject.