Well I finally got around to getting it installed (the file I got from your link was dreadfully unstable for some odd reason, strange). I must say there is one huge improvment in 3.1… SPEED! SonicStage 3.1 boots at least twice as fast on my computer as 3.0 did and the interface responds much quicker. This alone is easily worth the upgrade.
Also native MP3 encoding (with higher bit rates then the plug-in) is a blessing, its something I’ve been waiting for since SoniceStage was called OpenMG Jukebox. It seems Sony is heading in the right direction finally when it comes to digital music (especialy since they abolished that horrible check-in/check-out system a few version back).