It's unfortunately only sorta, kinda that metric. How quickly and precisely that magnet is able to move the diaphragm depends a lot on the amplifier as well. And other things. For example, when powered by a solid 50W amp, these small and somewhat inefficient DIY speakers are surpremely detailed in a small or medium room. They just need a solid amp to do it. They also have ribbon tweeters, which have some disadvantages, but also crazy advantages like being incredibly stiff and unburdened by a dome tweeter's need to flop around on a little foam rubber surround ring.Awesome again. (bell sound) I had these two ideas rolling around in my head, but I did not realize "sensitivity" was that metric.
In my experience it's fairly safe to assume that high-efficiency speakers have that sort of magical "effortless" quality. Though one can't assume that lower-efficiency speakers lack it. Personally, I'm planning on sticking with 90dB+ efficient speakers when possible in the future. But not as an iron clad rule.