I thought I heard somewhere that the A/D in the UA-5 is the same chip as the one in the Mini-Me.
As far as it not being bit-perfect, that's only true when you're giving it a digital signal (like from a D8 or the like). The reason it isn't bit-perfect is because it resamples digital sources. If you're giving the UA-5 an analog signal then it's not an issue because there's nothing to resample.
hope this helps,
Drew