I believe MusicMatch actually does use the FhG codec (at least the more recent releases of MM). However, I didn't see any mention of what version of MM they used or what modes they used (normal, high quality, etc).

I know I have seen various reports of known quality issues with the FhG codec that was used in MM releases around 5.0 and 6.0 - the issues crop up when using the high quality encoding modes, even at the higher rates... the main issue being pronounced high frequency distortion/artifacts. The last I remember seeing is that most of these were fixed in a newer version of the FhG codec that came in MM 6.1 or something.... . So if they don't have the latest and greatest MM release, this may have been a factor in their test results as well.