I come down on the side of, if the new technology is coupled with the maximally efficient design the sound has to be better. This assumes that you have the space, neighbors, spouse and fortitude to enjoy it
My reasoning goes like this;
Assume that you acquire a superior driver(s), design a no compromise enclosure and power it with an amplifier that is double or more of the rated capability of the drivers, place it in an optimal location in the room. The coupling of the driver to the enclosure will undoubtedly provide maximal efficiency. Generally one of the rules in speaker design is that the more power required to attain a specific nominal SPL the greater distortion, and the lower the dynamic headroom.
The distortion comes from everywhere, the electrical outlet, amplifier, overheated voice coils etc. When you add in the squaring of power to yield 3 db of SPL you can see that the headroom disappears rapidly as well.
If you use the same driver with the same or different electronics and compromise the enclosure, additional power will be required to acheive similar spl. At a minimum the dynamic headroom will be reduced, I also believe that distortion will be increased.
I guess what I am trying to say is that I believe if you couple "old school" with new technology you can get better results than either one separately. By way of example, I give you this;
http://www.decware.com/newsite/mainm...alSO.htm&intro
Paul