in my opinion about rev.18:
NeoGamma works well with DVD Backups,USB Functionality however doesn't work anymore.
Gamecube backups work flawlessly with the GC Backup Launcher.
USB Games can work only on USB Loader GX on this new revision (both WBFS and FAT partitions).
Metroid Prime Trilogy Game by default gives disc error on USb Loader GX.
If you wanna install it for terms of new changes in this revision,you can try it,otherwise stick to rev. 17.