You are probably right that the distortion performance is "good enough" for the medium. In absolute terms, and compared to contemporary ADC's, however, it is not very "sexy" from an engineering standpoint.
In the end this device might be one of the compromises one has to accept, as the huge functionality may outweigh the mediocre technical spec.
It does the job well. Making records sound almost as good as CDs and making slightly damaged records listenable.
It makes poor quality records sound good. Good quality records sound great. Great quality records sound awesome. I recommend the Waxwing over every other component I know about for increasing audio quality of records.