Diki
I understand what your saying but I don't think its a big problem. Anything new just gets added to the end of the Performance list. I knew this when I did my input for Unrealbook and wrote the list number on each song. I have everything in Alphabetical order in Unrealbook and thats what I work from.
I really happy with this, choose a song and I'm ready to go quickly., no down time between songs.
I use editedstyles for a number of songs and not song specific performances. My performance lost is around 80 styles.