About a year ago I was looking to move my servers from Fremont, CA (Hurricane Electric) to a more local provider. I went with Synccast in Anaheim.
Its been a year and I must say that I have never had any bandwidth related or power related down time, the quality of data/bandwidth service has been a 9.5 (just 9.5 because nobody gets a 10) The data center is not the most impressive I've seen, but quite functional. I came from HE Fremont which is an amazing data center to look at, maybe not the most reliable though, I'll give up aesthetics for quality anytime.
I have not had to use their tech support as I am close by and can repair any server related issues my self.
Just though I'd let you know they are a very viable option in Southern California.
HE.net is pretty good, but if you looking for SOCAL and gave 9.5 to your existing/current SOCAL datacenter - what you have to move ? Yes, here is few DC's around here, but they either pretty expensive (like Mzima) or not so good (CalPop).