I agree with this part of your statement. One solid piece of wood will resonate better due to the fact that there are no interruptions in the vibrations. This is the same basic principle as a full splice vs a half splice.
Theoretically I agree, but you would be hard pressed to identify which cue was cored or not, or with what in actuality, much less determine which is better. Just as identifying different joint configurations in a blind test has proven no absolute perceivable difference, so too is the effect of coring. The main reason coring is so widely accepted today is for this very reason, coupled with stability and consistency.