if you go over 100 mark, the remaining apps will be limbo. only after placing the apps in folders, will it rebuild the database a little more. if the app.db does get corrupted, it will rebuild the database. if you have everything sorted in a specific way, you might lose that. though, I've seen some instances where custom icons are removed but the icon arrangement remains the same. I wouldn't worry about corruption though as the system will correct it automatically. I believe a flag is placed on the memory card when the system needs to rebuild the database. that's how it is with the ps3 (err.mms?) though, I do recommend backing up the app.db in ur0:shell/db/app.db in ensure you don't have to go through sorting again. then, the appmeta ur0:appmeta in case you use custom icons that you don't want removed.