I was actually able to run over to the Magic Kingdom after class to try out Space Mountain with the new audio.
Having just ridden Disneyland's version of the popular ride (multiple times) during my California trip, I was convinced that the West Coast version of the ride has just slightly bested our ride thanks to its audio and quality projections. After riding Florida's Space Mountain today, I can honestly say that we are once again on top, without much contest. The new audio is just that--its brand new. Best described as a "rave in space," the new audio is triggered by each train's passing, making for a more personal audio experience, although the groovy backtrack (with an ominous sounding "Space. Space. Space Moutain" DJ'd into the track) runs overhead so that the entire dome is engulfed in sound.
It used to be that in space, everyone could hear you scream. Now, all you hear is a fantastic, catchy audio track that you can't help but bounce to as you fly out of your seat.