yes, I was able to demo the multibit, and I owned the 4490 for a while. The 4490 was a bit more generous with pop music, while still being very analytical. The multibit somehow seemed dryer. The multibit's soundstage also seemed to be more extreme, like it was large, but placement within it was a bit blurry, sometimes giving the "everything is hard left, right and center" feeling with less nuance in location than the 4490. The 4490 everything seemed sharply placed within the sound field, I felt like I could tell exactly where everything was. With the multibit things seemed less precise location wise.
But on really well recorded binaural music, the multibit could *really* shine, with an expansive soundstage that bested the 4490. Problem was I don't own that much binaural music. The multibit may have also been a bit more accurate up and down. The 4490 presented music a bit high in the soundstage, like you're seated really low looking up at a high stage. The multibit seemed a bit more realistic in that regard.
Now all of that sounds extreme, but it was very, very subtle as well. They're both great DACs, but I definitely think the 4490 is not only a better value, but is a flat out better, more versatile DAC. For whatever reason I don't think the multibit technology really clicks until you get to the GuMBy.