Bass Vs speaker efficiency

'Tight' bass is a coloration and has nothing to do with efficiency.

I think when many people refer to “tight” bass they are trying to express a juxtaposition to the perhaps more common “loose bass”.
 A sealed box will often provide tighter bass than a ported box, but if comparable bass output is to be achieved, the sealed box will typically do it with less efficiency.

I think when many people refer to “tight” bass they are trying to express a juxtaposition to the perhaps more common “loose bass”.

Its a good point. I've just not heard 'tight bass' in real life, only in stereos.

In general,  low bass extension comes at a cost and that is Sensitivity.  This is only a generalization, overall, the balance of mass vs motor tells the story, but regardless of the woofer,  anytime that you add mass, FS goes down and so does Sensitivity.  

I think many associate tight bass with speakers that don't go very low, and many times this is very efficient low xmax woofers.   Much more to it than what I am pointing out here, but this thought process persists.