Any experience with Vanguard's state-specific money market funds?

[faust]

I'm planning on starting to sock away some money into a money market fund for use for an eventual home down payment.

When looking into what Vanguard has, I saw that they have a couple of state-specific ones (CA, NJ, NY, PA). I live in CA. The selling point appears to be that the state-specific ones give returns exempt from both federal and state taxes. I know that high returns aren't the goal of MMFs, but I figure every little bit helps. Is there anything I'm missing/any downsides I'm not considering to picking the state-specific one over one of the general ones? The CA one has the same expense ratio as the Prime Money Market Fund (0.16%).

Thanks to all in advance.

[artemis]

The state-specific MMs probably carry a bit more risk (as they're limited to investing in munis from only that particular state; that's how they get the state tax exemption on the gains), but since no MM account is FDIC insured, I don't think the small difference in risk is something to obsess over, as any MM can break the buck.  If I was in your position, I'd go ahead and use the CA-specific fund.