Maybe my recall is faulty but I'm pretty sure that the PD8 Transitions basically faded image 1 out and image 2 in AND, specifically, faded the audio out and in as well.
I have spent a long long time with PD9 manually fading the sound out and in on hundreds and hundreds of transitions. Maybe the two versions of the transition on PD9 are acceptable to more editors BUT I would personally like a return to the PD8 version, at least as a third alternative.
GR