SGC doesn't have quite the same level of metadata capabilities that SFC has, but Google actually recognizes the OpenGraph metadata generated by Simple Facebook Connect.
For this reason, if you're using SFC, then SGC will recognize that and *not* generate extra meta data, since Google works with the FB metadata just fine (better, in some ways).
If you're not using SFC, then SGC will try to generate appropriate metadata, but as I stated, it's an early version. It simply doesn't have the complex meta capabilities that I've built into SFC yet.
So for the time being, I recommend running SFC for Facebook connectivity, and then you get the nice meta to be handled by Google as a bonus.