Overall, it may not be that the main reverbs have changed that much. It isn't the sound of the reverb, so much as how much is slathered on.
Most comments, and most of what I have heard about it hasn't been the same amount of reverb is used, just that it sounds better, it's that LESS overall is used.
Its 2 parts Diki, baartmans explained it nicely in the demo.
A sound is build from several parts... One is the samples and the other is the effects... There is dsp, chorus, reverb EQ... Now with the effects overhaul, they dont have to cover up the weakness of the other effects with a lot of reverb, all the instruments stand out much more..
On top of that the reverb itselves got vastly improved, with the old reverb all the notes espescially when played fast created a kind of blanked to cover up the sound. With the new reverb every single note gets to stand out much clearer in the reverb. As an example he played a fast piece of piano music to indicate what he meant.
But its important for everyone to see that the effects are atleast as important for the overall sound as the samples.. And this allows the T5 to sound much more alive and sparkling and thus more like the PA3x then a T4...