The city has (imo) a psychotic driving culture, but is still roughly middle-of-the-road in us news and world report's ranking of most dangerous US cities to drive in.
Large speed deltas are (conjecture I haven't bothered to research) probably unsafe under any conditions. Exceeding safe speeds for the conditions is obviously dangerous, but the size and design of the road and it's lanes are some of those conditions.
I don't particularly care which, but in order to minimize speed deltas I do think it should be incumbent on the state to either set low speed limits and fastidiously police them or else set speed limits that are close to the natural speeds a given road supports to cut down the gap between people who drive the road as it feels and those who drive the signage.