Why would you spend big money on a rain jacket in SoCal? I would go for the lightest thing possible since you are most likely not going to use it much anyways.
In my experience, and I have used eVent, Gore Tex, Membraine Strata, Precip,Dri-Ducks and some propitiatory Mont-Bell membrane, and you know what in a long sustained rain, all of them suck. Now I will admit that I hike in areas with high humidity, which makes it hard for any "breathable" jacket to do its job.
I currently have 4 wp/b jackets (I know I need to sell some!)
OR Zealot (GT Packlite)
Marmot Essence (Membrane Strata)
Mont-Bell Versalite (???)
The one that goes with me on 90% of my trips, the Dri-Ducks. Yes the fit sucks, the hood is terrible, it is fragile (though with some patches mine has over 1300 trail miles on it), but it seems to work as well as anything and it is 5.1oz.
For SoCal, I would get either Dri-Ducks, or another really light jacket like the Helium II, and call it a day. There is no perfect rain jacket, you will overheat and sweat while hiking in any of them. They do however keep you warm in a cold rain.