High vs. Low Efficiency Speakers

i own a pair of montana xp speakers they are rated at 92. i think that is pretty efficent and the sound very musical with any kind of music you want to play. they have awsome slamming bass. awsome midrange and treble

Are there benefits / disadvantages to either?))
Typically ext ream High efficient speakers with multiple drivers in the same pass band tend to achieve their
amplitude or efficiency at the expense of clarity by smearing which in my opinion sounds worse at low volume.
A well designed point source speaker with an easier load for tubes would be what I think you are looking for.
((I listen primarily to classical and prefer tube amps, does this lead me toward one speaker over another?))
I would take a look at the more well known mainstream successful high end designs that match your preferences.
((Lastly, I try to keep the music at a fairly low volume -- need to protect the hearing!))
Just remember a coherent speaker wont need the treble jacked up to balance fix the bump in the bass

If you like tube amps, a high efficiency speaker with a benign impedance curve is a no-brainer.

Regards
Paul