Maurice- Most people on this forum just focus on cashflow, in areas that get little appreciation. In decent parts of CA (especially the Bay Area) you need nowhere near 50% of rents to cover expenses. For one, vacancies are lower here. Also, higher rents per unit drastically effect expenses. Example. Tenant leaves and say you need to invest $2000 in paint and minor updates. That could be 4 months of rent in Texas, 1 month in CA. And in TX you would need 4x more units to equal 1 in CA, so your repair exposure is x4. So yes, there you want 50% ratio, but certainly not in the Bay Area.
And as for prices, if you think Oakland is bad, SF is worse! People on DP want 2% of prop cost to equal 1 months rent. In SF it's more like 1/2%! Terrible deal right? Then why are there so many investors clawing their way to buy here? (I'm also looking to get into another multi unit in SF.) Cause they quietly know that future appreciation in SF is substantial. Oakland (although I don't specialize in it) is similar in potential, certainly compared to cashflow friendly areas with little appreciation.
I'll quote you: "One person told me he covered the rent in the unit he lived in as a owner occupier until he could refi out his loan and take money out to buy another property...risky! But they all do that or try to do that."
That is exactly how many do it in CA. Your friend was able to buy another property from appreciation. That's huge!
Ultimately you have to run your own numbers. But if you can get into a decent part of Oakland for little down, secure a low rate 30 year fixed loan, and manage the cashflow mid term, you have a decent chance of setting yourself up nicely 3-5 years from now. Rents will inevitably go up in next 2 years, and $1000 in added rent (over 4 units is not a lot) will increase your property's value by (using 12-14 GRM) $120,000-140,000. As long as your buying in a decent part of Oakland, I think you strategy is solid.