I've lived in a Unitary system (UK) through a bunch of different variations of a Federal system (NZ, Australia, Switzerland, USA, and even EU in a way) -- worth noticing Switzerland apparently was the inspiration for the Californian direct democracy.
Each really favors a different set of circumstances. It was shocking in Switzerland to be there for a few votes where people voted to very directly raise taxes. I couldn't imagine that in Australia.
Splitting up California has some appeal as a bar-room hypothetical -- but in some ways aggregating state powers might be better. e.g. Education, policing, infrastructure, is very, very, (very) fragmented. Many of these issues are because they are either directly or indirectly locally administered. I don't see this really reducing that fragmentation.
In fact -- I often wonder if the Bay Area would be better off as a combined municipality. Probably for issues like infrastructure, certainly.
Interested in the counterpoints to all that.