30's ain't all one turf, it depends on whether you're talking about dogtown or ghost town.
And yeah East Oakland rap tends to be faster (beats and lyrics) on stripped down production with a lot of bass, i.e. soundtracks for sideshows. West Oakland tends to be on some slower darker shit, which it is... It's slower in the West than in the East but it's also more depressed. North Oakland be on some whole other shit... There's a big East Coast influence there which probably originated from the backpack rap scene in Berkeley in the 90s/early 2000s centered around Amoeba and Berkeley High back when CDs were actually moving and having your CD at Amoeba was a bigger deal. They were probably crossing paths with underground "Hip Hop" rappers and the Hip Hop scene in general more than rappers from the west or the east not named Hiero.