Mark Racicot came across very well supporting the President in 2000.
Racicot is definitely not a conservative. He had his own David Souter moment as governor when he appointed who has turned out to be the worst, most leftwing member of the Montana Sup Court (can't remember his name right now), and as RNC head he needlessly insulted social conservatives.
So yes, I'd definitely prefer Rehberg.
But if it were Racicot vs either Dem, then I'd favor Racicot, because he'd at least vote for good Sup Court nominees, whereas both Tester and Morrison said they would have voted against Alito.
Ideally, Burns would get out, and then Rehberg would step in and hold the seat. Then maybe Racicot could do in 2008 what so many wanted him to do in 2002 -- take on Baucus.