sorry,,, my linguistic limitations mean i couldn't understand the posts above so forgive me if i'm repeating something that was already said,,,
my understanding of 'Spaza' as explained to me by Middle Finga (a self-proclaimed 'Spaza' artist) is this,,, a Spaza shop is a place where you can get bits and pieces in the hood - musically, Spaza is Hip Hop where the rapper uses bits and pieces of different languages - english, xhosa, zula and street slang.
Thematically, I also see 'Spaza' as music that is reflective of life in the hood. For example, I don't think Spaza cats would rap about metaphysical, esoteric stuff.
Having said all of that, I don't think I've ever heard Driemanskaap rhyme in english but they are referred to as 'Spaza'.