For 107.3 - Keep WAAF there until the station is on its last leg. Few listeners in Greater Boston are going to tolerate a static-riddled FM station to hear Rock music or any other mass appeal format. Once WAAF has outlived its usefulness, sell the darn stick to EMF.
WBRU covers a lot of the territory WAAF's signal is strongest in. What EMF wants is a full-market Boston signal.