Just in case this was a concern: I've done a file compare between the Windows 7 Home Premium Upgrade media and the Windows 7 Family Pack media and they are indeed identical. The weird thing is that you only get one product key with the Family Pack, so the only real difference is up in the cloud: The Family Pack product keys can be activated three times.
From a practical standpoint, this means that any discussion about Upgrade media applies equally well to Family Pack, I guess.