Calling all Speaker Guru's!?

I'm curious - Would a Speaker with a 100 db capability, with a +/- 10 db SPL variation, produce a Decent 110 db or a Horrible 90 db? Also, Could anyone offer name(s) of Guitar Speaker Companies/Type of Speaker that would have +/- 3db or better? I'm looking for the Highest Efficiency replacement Speaker for a Guitar Amp - Speaker will need to be 12", 8 Ohm and able to handle 75 Watts. ~Thank You in Advance!