Alex R. Just for giggles I did some quick math to determine 2012 expense ratios (Expenses/Gross Income) for a couple of my properties for which I have the data handy.
4-Unit: 52%
SFH: 35%
2-Unit: 78%
2-Unit: 34%
2-Unit: 28%
Sort of a scatter-shot...and it will be different in 2013 as new maintenance and repairs are done on some units, and other units require less upkeep as compared to this year.
My experience (and I'm by no means the most experienced REI) is that the 50% rule is pretty close for my portfolio. Maybe less in the beginning on a newer construction...maybe more on older properties, but right around 50% over the long term (I have a property manager so that accounts for 10%).
In looking at the numbers you supplied, it looks like the owner's stated Expenses/Gross Income is about 30%, thought I agree with most posters who feel that $67/month ($804 annually) is low for property insurance. Also, I think that 1% vacancy is very low. If you account for higher insurance and factor in and extra 4-5% vacancy, you're probably right around 37-40%...which is pretty close if you intent to manage the property yourself.
I'm by no means an expert on property in California and my experience in Ohio may not be relevant. Good luck.