If you prefer the original narration (at the time of this post) you can still download the original audio and original conversations by clicking the "Download THIS Audio" link directly below the play button. Personally, I like hearing Kenny Squire's narration and the original flow of the script. Plus, by hearing an English-speaker speak Japanese (Kenny) followed by a native Japanese speaker (Sayaka), the contrast between the two accents indicates where you fall in the pronunciation spectrum. So if I sound more like Kenny then I need to work on my pronunciation. If I sound closer to Sayaka then I'm on the right track.
Personally, I'm going to complete the audio course using the original audio and when I eventually make my way through the program a second time, I will use the new audio. That way I get the best of both worlds. Cheers!