Low-sensitivity speakers — What's special about them?

I'm building a system for a smaller room (need smaller bookshelves), and I did a bunch of research and some listening. I am attracted both to the Dynaudio Evoke 10's (heard locally) and the Salk Wow1 speakers (ordered and I'm waiting on them for a trial). I have a Rel 328 sub.

Here's the thing — both of those speakers are 84db sensitivity. Several people on this forum and my local dealer have remarked, "You should get a speaker that's easier to drive so you have a wider choice of power and can spend less, too."

That advice — get a more efficient speaker — makes sense to me, but before I just twist with every opinion I come across (I'm a newbie, so I'm pathetically suggestible), I'd like to hear the other side. Viz.,

QUESTION: What is the value in low sensitivity speakers? What do they do for your system or listening experience which make them worth the cost and effort to drive them? Has anyone run the gamut from high to low and wound up with low for a reason?

Your answers to this can help me decide if I should divorce my earlier predilections to low-sensitivity speakers (in other words, throw the Salks and Dyns overboard) and move to a more reasonable partner for a larger variety of amps. Thanks.
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A phd in a post, out for beachside valentine lunch. Our path similar!
will write more later!!!
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@larry5729  I will. I’m glad you think the Salks will be good. I went listening today to some amps... and heard some Spendor A4s and some Elacs S61. They didn’t do much for me, though they sounded good. Looking forward to getting the Salks, someday. I ordered them Jan 9. 
With the vast majority of typical speakers one can make a speaker's impedance more linear by lowering it's impedance, which can allow amplifiers to provide a more linear frequency response through those speakers. But doing so will decrease the speakers sensitivity.

One will be hard pressed to find high sensitivity speakers that can produce respectable step response or square wave response.

There's a lot more to speakers than sensitivity alone.
Thanks, unsound. That helps me make a bit more sense of the measurement which the page for the speakers I ordered list. I bought them for the reputation and reviews --and the notion they'd be sized well for my listening room, which was confirmed by the maker. It was only later on that I realized the sensitivity was low. Here are the stats/landing page for that speaker. http://www.salksound.com/model.php?model=WOW1