I received the GEN 5 bimby. It sounds better, but there is still room for improvement. The groove is still lacking. If I had to put exact numbers on how it sounds, I would say it grooves only to 50% of what you would feel when you listen to the music in a club, in your car or with your headphone plug in a portable CD. Even a mp3 player like my samsung galaxy give me more feel of the music. On the other hand, the depth, details, well, the "digitalness" of the sound is improved. the image, stage, richness is improved. This is exactly what you would expect and what you pay for.
This is not an endgame for USB but an interesting step.