Two of my six Weaver GG1s have QSI sound and I have QSI sound in an upgraded Williams brass J Class. The sound is good quality. Many of those sounds went into early MTH PS locomotives and are regarded by some as still some of the best MTH sounds in certain locomotives.
The nice part about the QSI modules for Weaver is that is a removable board. If the sound goes out, the locomotive still runs.