Some genres like blues has practically been defined by white "ethno-musicologists" with "rural"/"authenticity" biases and other acts have their importance defined strictly on how influentil they were on white rock; see 50's rock'n'roll and the status of the regular Chuck Berry/Little Richard-types versus acts from the same era-think everyone from Jackie Wilson to Roy Brown -that were just as big-if not bigger-on the R&B charts and who might have had a much bigger impact on *black* music than the canonized names.

Doo-wop is another "genre" I think would have been viewed in a MUCH different light if there were black musicologists covering stuff and writing music history...

In jazz, there were some black writers in the 60's (think LeRoi Jones and AB Spellman) but they were what I guess could be considered "bohos" and their writing on free jazz and stuff didn't seem to make much impact on jazz-writing as a whole...

Outside of Nelson George and-if he counts due to his "esoteric" tastes-Greg Tate, Hip-Hop and its associated generation seems to be first time I can remember that you have a large amount of black musicologists writing stuff...