I just showed you that the forum underestimates Democratic performance. What part of this is hard to understand?
When "everybody" thinks Romney is going to win Florida, "everybody" is underestimating Democratic performance.
So when someone (you) says, "The forum overestimates Democratic chances/performance because there are more Democrats," they are ignoring facts.
That doesn't change the fact that, as Del said, Republicans are favored in at least five races, and have excellent opportunities in many more, yet most Democrats on this forum still say that Democrats are likely to retain the Senate.