ive had it for the last couple of weeks....havent really messed with it though. i saw something on the SSSPSX site about memory usage and the new beta...apparently it's lower (it's in Japanese...go venture and read it if you dare ) but i dont know. i'll wait to the official release to actually use it...1.41 has been working fine for me.
btw, apparently its an unofficial beta release...it was mentioned in the forums that the devs might not even want this leaked.
no improvements in sound, they havent added the gaussian interpolation yet...but it should have better CPU usage which is nice because Eternal Lite sounds crappier. so maybe people with slower CPUs can use Eternal and still get good performance.