L0K1  i did not have trouble unstuffing with stuffit10 under 10.4.3 and the disk did mount, but iPlaylist would not install via the Installer app (could not find /.Data/iPlaylist).

so i checked the dmg with disk utility. disk utility stated that the disk required repairing, so i ran a repair. the Installer app was still unable to install iPlaylist (same error).

i used TinkerTool to show hidden files and just went in and got it myself - on the dmg in .Data you'll find the iPlaylist app and you can just drag it to your Applications directory. that worked and the app runs fine. perhaps that will help you.  
(Version 1.0)