i dont think atlanta was out like that back then. miami took off with electro shyt in the early/mid 80s. bass music, electro, all that 808 heavy shyt contributed to the current sound of hip hop.
i wouldnt consider miami part of 'the south' even considering its geographical location. miami has been on par with other major metropolitan cities such as la, chicago, ny, detroit...
Yeah, atl wasn't gay capital back then. Things changed after the olympics went there in 1996, and Outkast/Goodie Mob/Organized Noize got big, Atlanta got more media attention.
Miami is still the south, in the 80's they wasn't making any noise with the electro music, it was L.A. that was coming up with that sound. Plus, Miami, and Atl, both was about booty music. That sound was an off shoot of "planet rock" by Afrika Bambatta, and the soulsonic force. L.A. Atl, and Miami kept that style while NYC moved on, which is why rap stayed in NYC. It wasn't until Ice-t, and NWA, that things changed for L.A., and the rap style of boom bap became part of L.A.
With Miami, it really didn't change until Poison Clan, Home team, Society, Mother Supreme, and officially with Trick Daddy. 2 live crew was a mix of booty music, and classic rap.
With Atl, it was Kriss Kross, a group with a guy with dreads, and a fat guy, I forget their name, then Outkast.