I can reccommend the Souljazz set World of cos it finally allowed me to own Go Bang #5 on cd after not being able to play my 12" for years. Love that song. The rest of the cd's pretty cool too.
I have Another Side of Arthur Russell somewhere, I think the John Martyn vcocal thing's more evident there. While not carbon copies that soft deep-voicedness is somewhat similar
Stevo