No big loss given 5.2, 8.2, and 8.3, but FWIW, KDFW is no longer broadcasting weather radar on subchannel 4.2.
If this had been any network other than Fox, dropping a subchannel would've let the station reduce their compression on the main HDTV channel, thus improving the picture quality a bit. But my understanding is Fox is different: they have a fixed-bandwidth network feed with room for one subchannel, so the PQ remains the same whether the affiliate uses the subchannel or not. (It might improve PQ on local HD content, though.)
If this had been any network other than Fox, dropping a subchannel would've let the station reduce their compression on the main HDTV channel, thus improving the picture quality a bit. But my understanding is Fox is different: they have a fixed-bandwidth network feed with room for one subchannel, so the PQ remains the same whether the affiliate uses the subchannel or not. (It might improve PQ on local HD content, though.)