Excellent choice of a bellweather. I can't think of a better one, at least for open seats. Where incumbents are in play, it gets a bit more complicated.
For incumbents, I might chose Chocola's race as the single best indicator. Drake would be my second choice. Pryce would be my third choice. The other choices high on the list don't fit either because their district voted for Kerry or they face a rematch from a previous popular incumbent who held the seat previously or because the incumbent has other unique unfavorables that make him vulnerable not related to national environment. These 3 are arguably the most vulnerable of the ones that are in the fight of their life only because it is 2006.