I have seen it suggested that there was a technical difference between gospel and blues. That blues tended to be constructed using this version of the pentatonic scale:
DFGACD
While gospel tended to wards structures based on the CDEGAC scale.
Now, obviously this is an over-simplification, most blues and gospel songs are not purely pentatonic, but the predominant notes of a lot of songs follow a pentatonic pattern, with just a few passing noted filling in the gap. And of course the variable third is used a lot in blues, so the F in the "blues pentatonic" should be conidered as of variable pitch from F to F#. But I would say there is a germ of reason in this theory(I dont know who first proposed it). Jerry, youve got a foot in both camps, have you come across this idea?