My use cases were:
1. I entered all the CD data for a CD (the default download was completely
wrong) before realising that I hadn't installed gstreamer0.8-lame in order to
rip to mp3, so I had to exit Sound Juicer, installed gstreamer0.8-lame restarted
Sound Juicer and then discovered I needed to reenter all the data.
2. I occasionally need to rip a CD twice, usually because I want to store it in
ogg for my Free Software using house to listen to, but also want it on mp3 so
that I can listen to it on my proprietry solid state mp3 player. I usually don't
do these rips at the same time.
The third one I haven't encountered:
3. In the event of a crash of either Sound Juicer, X, or my computer, I'd rather
not do that data entry again if it can be avoided.